Ophthalmology – Acquired Nystagmus

Basics

Description

Acquired nystagmus is a repetitive, involuntary oscillation of the eyes that develops after infancy or after a period of previously stable ocular motor function.

It may be:

• Constant
• Intermittent
• Cyclic
• Monocular
• Binocular
• Asymmetric or dissociated

Nystagmus develops when the eyes cannot maintain a stable position of gaze and drift away from the desired target.

The oscillation may be:

• Pendular – movements have approximately equal velocity in both directions
• Jerk – slow drift in one direction followed by a corrective fast phase

Acquired nystagmus often causes:

• Oscillopsia
• Reduced visual acuity
• Imbalance
• Vertigo
• Ataxia

Epidemiology

Acquired nystagmus is uncommon.

Population prevalence estimates for all forms of nystagmus are approximately:

240 per 100,000

The prevalence of individual acquired forms depends strongly on the underlying neurologic, vestibular, toxic, or structural disorder.

Risk Factors

There are no single universal risk factors because acquired nystagmus has many causes.

Potential predisposing conditions include:

• Cerebellar disease
• Brainstem disease
• Multiple sclerosis
• Stroke
• Vestibular disorders
• Medication toxicity
• Alcohol or sedative exposure
• Nutritional deficiencies
• Craniocervical junction abnormalities
• Tumors
• Severe visual pathway disease

Genetics

Most acquired nystagmus is not inherited.

However, inherited neurologic conditions may produce nystagmus, including:

• Episodic ataxias
• Mitochondrial disease
• Leukodystrophies
• Congenital cerebellar disorders

Pathophysiology

Stable vision requires the retinal image to remain relatively stationary.

Three major systems stabilize gaze:

• Vestibulo-ocular reflex
• Visual fixation system
• Neural integrator for eccentric gaze holding

Failure of any of these systems may cause nystagmus.

Vestibulo-Ocular Reflex

The vestibulo-ocular reflex stabilizes vision during head movement.

Abnormal asymmetry of vestibular tone may cause:

• Slow drift of the eyes
• Corrective fast phases

This produces vestibular jerk nystagmus.

Visual Fixation

Visual fixation stabilizes the target through:

• Corrective eye movements when retinal image drift occurs
• Suppression of unwanted eye movements

Severe visual pathway disease may impair these mechanisms.

Neural Integrator

The neural integrator converts brief eye-movement commands into sustained tonic signals that keep the eyes in eccentric gaze.

Important structures include:

Horizontal gaze holding

• Medial vestibular nucleus
• Nucleus prepositus hypoglossi
• Cerebellar flocculus and related pathways

Vertical and torsional gaze holding

• Interstitial nucleus of Cajal

Failure of the neural integrator causes the eyes to drift back toward primary position, followed by corrective saccades.

This produces:

Gaze-evoked nystagmus

Pulse-Step Mechanism

A saccade requires:

• A pulse of neural activity to rapidly move the eye
• A step of tonic activity to hold the new position

If the step is insufficient relative to the pulse, the eyes drift back after the saccade.

This mismatch may produce:

• Glissades
• Gaze-evoked nystagmus

Classification

Important forms of acquired nystagmus include:

• Peripheral vestibular nystagmus
• Downbeat nystagmus
• Upbeat nystagmus
• Torsional nystagmus
• Periodic alternating nystagmus
• See-saw nystagmus
• Acquired pendular nystagmus
• Gaze-evoked nystagmus
• Oculopalatal tremor

Symptoms

The hallmark symptom of acquired nystagmus is:

Oscillopsia

This is the false perception that stationary objects are moving.

Patients may describe:

• Shaking vision
• Jumping images
• Blurred vision during head movement
• Difficulty reading
• Poor balance
• Vertigo
• Nausea

Oscillopsia is much more common in acquired than congenital nystagmus because patients have not adapted neurologically to the ocular oscillation.

Peripheral Vestibular Nystagmus

Peripheral vestibular disease produces a characteristic jerk nystagmus.

Typical features include:

• Horizontal-torsional direction
• Unidirectional fast phase
• Worsening when looking toward the fast phase
• Suppression with visual fixation
• Increased intensity in darkness or with Frenzel goggles
• Association with vertigo and nausea

Alexander’s Law

Peripheral vestibular nystagmus usually follows Alexander’s law:

The nystagmus becomes more intense when the patient looks in the direction of the fast phase.

Benign Paroxysmal Positional Vertigo

BPPV is a common peripheral vestibular cause.

It most commonly involves the:

Posterior semicircular canal

Typical findings include:

• Brief positional vertigo
• Characteristic torsional-upbeating nystagmus during positional testing
• Latency before onset
• Fatigability
• Short duration

Dix-Hallpike Test

The Dix-Hallpike maneuver is used to diagnose posterior canal BPPV.

A typical response includes:

• Vertigo
• Torsional-upbeating nystagmus
• Brief latency
• Fatigability

Treatment of BPPV

The main treatment is:

Canalith repositioning

Common maneuvers include:

• Epley maneuver
• Semont maneuver

Routine long-term use of vestibular suppressants is discouraged because they may:

• Delay central compensation
• Cause sedation
• Increase fall risk

Short-term antiemetic or vestibular suppressant use may be appropriate for severe symptoms.

Downbeat Nystagmus

Downbeat nystagmus is a central vestibular nystagmus in which the fast phase is downward.

It often becomes more prominent in:

• Lateral gaze
• Downgaze
• Convergence

It strongly suggests disease involving the:

• Cerebellar flocculus
• Vestibulocerebellum
• Craniocervical junction

Causes of Downbeat Nystagmus

Important causes include:

• Chiari I malformation
• Cerebellar degeneration
• Multiple sclerosis
• Stroke
• Brainstem or cerebellar tumor
• Craniocervical junction disease
• Hydrocephalus
• Trauma
• Toxicity from medications

Medication causes include:

• Anticonvulsants
• Lithium
• Sedative drugs
• Some antiarrhythmics

Metabolic and deficiency states include:

• Vitamin B12 deficiency
• Thiamine deficiency
• Magnesium deficiency

Episodic Ataxia Type 2

Downbeat nystagmus may occur with:

Episodic ataxia type 2

This is associated with pathogenic variants in:

CACNA1A

Patients may have:

• Episodic vertigo
• Ataxia
• Interictal downbeat nystagmus

Acetazolamide may reduce attacks in selected patients.

Treatment of Downbeat Nystagmus

Treatment should first address the cause.

Symptomatic medications sometimes used include:

• 4-aminopyridine / dalfampridine
• Baclofen
• Clonazepam in selected cases

4-aminopyridine is often one of the more effective pharmacologic options for persistent downbeat nystagmus.

Medication choice requires neurologic supervision because of potential adverse effects, particularly seizure risk with aminopyridines.

Upbeat Nystagmus

Upbeat nystagmus has an upward fast phase.

It usually reflects central pathology involving:

• Medulla
• Pons
• Midbrain
• Cerebellum

Causes of Upbeat Nystagmus

Important causes include:

• Brainstem stroke
• Multiple sclerosis
• Wernicke encephalopathy
• Cerebellar degeneration
• Tumors
• Behçet disease
• Drug toxicity

Treatment of Upbeat Nystagmus

Treatment focuses on the underlying disorder.

Symptomatic therapy may occasionally include:

• Baclofen
• Aminopyridines

Evidence is less robust than for downbeat nystagmus.

Torsional Nystagmus

Pure torsional nystagmus is uncommon.

It may occur with:

• Brainstem lesions
• Vestibular pathway lesions
• Ocular tilt reaction
• Skew deviation

It should generally prompt neurologic evaluation.

Periodic Alternating Nystagmus

Periodic alternating nystagmus (PAN) is a horizontal jerk nystagmus that periodically reverses direction.

The cycle typically lasts approximately:

1.5–2 minutes

before changing direction.

Causes of PAN

Associated conditions include:

• Cerebellar disease
• Multiple sclerosis
• Craniocervical junction disorders
• Visual pathway disease
• Congenital ocular motor disorders

Treatment of PAN

Baclofen is the classic treatment.

It may reduce:

• Nystagmus amplitude
• Directional reversals
• Oscillopsia

See-Saw Nystagmus

See-saw nystagmus is a disconjugate vertical-torsional oscillation.

Classically:

• One eye elevates and intorts
• The other eye depresses and extorts

Then the movements reverse.

Causes of See-Saw Nystagmus

Strongly associated with:

• Parasellar lesions
• Optic chiasm lesions
• Midbrain compression
• Congenital chiasmal abnormalities

It may be seen with:

• Pituitary region tumors
• Craniopharyngioma
• Severe chiasmal visual loss

Acquired Pendular Nystagmus

Acquired pendular nystagmus is strongly associated with:

Multiple sclerosis

It may be:

• Horizontal
• Vertical
• Torsional
• Elliptical
• Circular
• Dissociated between the two eyes

Other Causes of Acquired Pendular Nystagmus

Include:

• Brainstem stroke
• Cerebellar stroke
• Tumors
• Demyelinating disease
• Mitochondrial disorders
• Leukodystrophies
• Toxic exposure

Treatment of Acquired Pendular Nystagmus

Most commonly used symptomatic treatments include:

• Gabapentin
• Memantine

These can reduce:

• Oscillation amplitude
• Oscillopsia

Clonazepam may help some patients but often causes sedation.

Gaze-Evoked Nystagmus

Gaze-evoked nystagmus appears when the eyes are held eccentrically.

The slow phase is directed toward:

Primary position

It results from impaired neural integration.

Causes of Gaze-Evoked Nystagmus

Common causes include:

• Sedative-hypnotic medications
• Alcohol
• Anticonvulsants
• Cerebellar disease
• Brainstem disease

A small amount of endpoint nystagmus at extreme gaze may be physiologic, but persistent or asymmetric gaze-evoked nystagmus is abnormal.

Oculopalatal Tremor

Formerly called oculopalatal myoclonus, this is an acquired pendular oscillation associated with lesions in the Guillain-Mollaret triangle.

This circuit includes:

• Dentate nucleus
• Red nucleus
• Central tegmental tract
• Inferior olivary nucleus

Clinical Features of Oculopalatal Tremor

Ocular movement is often:

• Vertical
• Torsional
• Pendular

Frequency is approximately:

1–3 Hz

It may be accompanied by rhythmic movement of:

• Palate
• Pharynx
• Larynx
• Facial muscles

MRI in Oculopalatal Tremor

MRI may show:

Hypertrophic degeneration of the inferior olivary nucleus

This often develops months after the causative brainstem or cerebellar lesion.

Causes of Oculopalatal Tremor

Common causes include:

• Brainstem hemorrhage
• Brainstem infarction
• Cerebellar hemorrhage
• Tumor
• Demyelinating disease

Treatment of Oculopalatal Tremor

Symptomatic options include:

• Gabapentin
• Memantine

Other agents are less consistently effective.

Diagnosis

History

Ask about:

• Onset
• Duration
• Constant versus intermittent symptoms
• Oscillopsia
• Vertigo
• Ataxia
• Hearing symptoms
• Diplopia
• Headache
• Recent stroke-like symptoms
• Medication use
• Alcohol exposure
• Anticonvulsants
• Lithium
• Sedatives
• Toxic exposures

Neurologic Red Flags

Acquired nystagmus accompanied by:

• New ataxia
• Weakness
• Dysarthria
• Sensory loss
• Severe headache
• Cranial nerve palsy
• Altered consciousness

requires urgent evaluation for a central neurologic cause.

Examination

Characterize:

• Direction
• Plane
• Waveform
• Conjugacy
• Frequency
• Amplitude
• Effect of gaze
• Effect of fixation
• Effect of convergence
• Effect of head position

Fast Phase Naming

Jerk nystagmus is named according to the:

Direction of the fast phase

For example:

• Downbeat nystagmus → fast phase downward
• Right-beating nystagmus → fast phase rightward

Fixation Suppression

Peripheral vestibular nystagmus is generally:

Reduced by fixation

Central nystagmus is less likely to suppress with fixation and may persist or worsen.

Ophthalmoscopy

Direct ophthalmoscopy can sometimes make the movement easier to appreciate because the optic disc and retinal vessels provide a stable reference.

Video-Oculography

Eye movement recordings can objectively measure:

• Frequency
• Amplitude
• Slow-phase velocity
• Waveform

These may help distinguish nystagmus from saccadic oscillations.

Laboratory Testing

Routine laboratory testing is usually not helpful unless a specific cause is suspected.

Selected tests may include:

• Blood alcohol level
• Toxicology screen
• Vitamin B12
• Thiamine-related evaluation
• Magnesium
• Drug levels

depending on history.

Neuroimaging

MRI of the brain, particularly the posterior fossa and craniocervical junction, is often the imaging study of choice for unexplained acquired nystagmus.

Useful sequences include:

• T1
• T2
• FLAIR
• Diffusion-weighted imaging
• Post-contrast imaging when indicated

When MRI Is Particularly Important

MRI is strongly indicated for:

• Downbeat nystagmus
• Upbeat nystagmus
• Pure torsional nystagmus
• See-saw nystagmus
• New acquired pendular nystagmus
• Associated neurologic signs
• Suspected brainstem/cerebellar disease

Differential Diagnosis

Important mimics include:

• Saccadic intrusions
• Ocular flutter
• Opsoclonus
• Square-wave jerks
• Macrosaccadic oscillations
• Superior oblique myokymia
• Ocular neuromyotonia

Saccadic Intrusions

Unlike nystagmus, saccadic intrusions consist primarily of:

Rapid saccades rather than a slow drift followed by a fast correction

Examples include:

• Square-wave jerks
• Ocular flutter
• Opsoclonus
• Macrosaccadic oscillations

Ocular Flutter

Characterized by:

• Back-to-back horizontal saccades
• No intersaccadic interval

It may be associated with:

• Paraneoplastic disease
• Encephalitis
• Toxic-metabolic states

Opsoclonus

Opsoclonus consists of:

• Chaotic
• Multidirectional
• Back-to-back saccades

It may occur with:

• Paraneoplastic syndromes
• Neuroblastoma in children
• Autoimmune encephalitis
• Postinfectious states

Superior Oblique Myokymia

Produces:

• Brief
• Monocular
• Vertical-torsional oscillopsia

Patients often describe:

• Shimmering
• Trembling vision
• Brief episodes triggered by gaze

It is usually due to abnormal trochlear nerve excitability.

Ocular Neuromyotonia

Characterized by episodic tonic deviation of one eye, often triggered by prolonged eccentric gaze.

It is most often seen after:

• Parasellar radiation

It may affect:

• Oculomotor nerve
• Trochlear nerve
• Abducens nerve

Treatment Principles

Treatment has two goals:

1. Identify and treat the underlying cause
2. Reduce disabling oscillopsia or visual blur

Cause-Specific Treatment

Examples include:

• BPPV → canalith repositioning
• Chiari malformation → neurosurgical evaluation when symptomatic
• Nutritional deficiency → replacement therapy
• Medication toxicity → stop or reduce offending drug when appropriate
• Multiple sclerosis → neurologic treatment
• Stroke → vascular management and rehabilitation
• Wernicke encephalopathy → urgent thiamine

Pharmacologic Treatment

Treatment depends strongly on the nystagmus type.

Commonly used agents include:

Downbeat nystagmus

• 4-aminopyridine / dalfampridine
• Baclofen
• Clonazepam in selected patients

Periodic alternating nystagmus

• Baclofen

Acquired pendular nystagmus

• Gabapentin
• Memantine

Oculopalatal tremor

• Gabapentin
• Memantine

Medication choice should be individualized because adverse effects such as:

• Sedation
• Dizziness
• Ataxia
• Seizures
• Cognitive impairment

may limit treatment.

Treatments Generally Not Recommended

Older reports described symptomatic benefit from:

• Alcohol
• Cannabis
• High-dose anticholinergic drugs

These are not standard treatments because of limited evidence and substantial adverse effects.

Optical Treatment

Selected patients may benefit from:

• Prisms
• Contact lenses
• Refractive optimization

Prisms may shift gaze toward a position where nystagmus is reduced.

Null Point

Some patients have a gaze position in which nystagmus intensity is minimal.

This is called the:

Null point

Patients may adopt an abnormal head posture to maintain the eyes in that position.

Surgery

Extraocular muscle surgery may be considered when:

• There is a stable null point
• A disabling abnormal head posture is present
• Medical treatment fails

Procedures may shift the eyes toward the null position.

Surgery is less commonly used for acquired than congenital nystagmus.

Botulinum Toxin

Botulinum toxin injections into extraocular muscles have occasionally been used for severe acquired nystagmus.

Limitations include:

• Ptosis
• Diplopia
• Induced strabismus
• Variable duration
• Incomplete benefit

Therefore, it is not routinely used.

Retinal Image Stabilization

Special optical systems have historically been designed to reduce retinal image movement.

These are rarely used in routine practice because of:

• Complexity
• Limited practicality
• Visual field restriction

Follow-Up

Follow-up depends entirely on the cause.

Patients with new acquired nystagmus generally require reassessment of:

• Visual acuity
• Oscillopsia
• Eye movement characteristics
• Neurologic findings
• Treatment response

Prognosis

Prognosis varies.

Peripheral vestibular causes

Often improve or resolve, particularly:

• BPPV
• Acute vestibular neuritis

Central causes

May persist chronically, especially when related to:

• Multiple sclerosis
• Structural brainstem lesions
• Cerebellar degeneration
• Oculopalatal tremor

Patient Education

Patients should understand that acquired nystagmus is usually a sign of an underlying ocular motor, vestibular, neurologic, or toxic disorder, rather than a diagnosis by itself.

Urgent evaluation is warranted when nystagmus is associated with:

• New severe headache
• Weakness
• Dysarthria
• Severe ataxia
• Diplopia
• Loss of consciousness
• Other acute neurologic symptoms

Ophthalmology Pearls

• Acquired nystagmus usually causes oscillopsia; congenital nystagmus often does not.
• Nystagmus contains a slow drift phase; saccadic intrusions consist primarily of rapid saccades.
• Downbeat nystagmus strongly suggests cerebellar or craniocervical junction disease, especially Chiari malformation.
• Upbeat nystagmus suggests central brainstem or cerebellar pathology.
• Peripheral vestibular nystagmus is usually unidirectional, suppressed by fixation, and follows Alexander’s law.
• Posterior canal BPPV typically causes torsional-upbeating positional nystagmus and is treated with an Epley-type canalith repositioning maneuver.
• Periodic alternating nystagmus reverses direction every 1–2 minutes and often responds to baclofen.
• Acquired pendular nystagmus is classically associated with multiple sclerosis and may respond to gabapentin or memantine.
• See-saw nystagmus should raise concern for parasellar or chiasmal disease.
• Oculopalatal tremor is associated with lesions in the Guillain-Mollaret triangle and may show hypertrophic inferior olivary degeneration on MRI.
• Persistent new acquired nystagmus generally warrants careful neurologic examination and, when unexplained, MRI of the brain/posterior fossa.

Ophthalmology – Norrie Disease

Basics

Description

Norrie disease is a rare X-linked retinal dysplasia disorder that predominantly affects males and usually causes severe bilateral visual impairment from birth or early infancy.

It is caused by pathogenic variants in the NDP gene and classically presents with:

• Bilateral retinal dysplasia
• Abnormal retinal vascular development
• Retinal folds or tractional retinal detachment
• Retrolental fibrovascular masses producing a pseudoglioma appearance
• Severe congenital or early-onset visual loss

Extraocular manifestations may include:

• Progressive sensorineural hearing loss
• Developmental delay
• Cognitive impairment
• Behavioral or psychiatric abnormalities

Historically, the disorder has also been called:

Progressive oculo-acoustico-cerebral degeneration

Epidemiology

Norrie disease is extremely rare.

It:

• Occurs predominantly in males
• Has been reported in many ethnic groups worldwide
• Was initially described in Scandinavian families

Affected females are uncommon but may develop ocular abnormalities because of:

• Skewed X-chromosome inactivation
• Structural X-chromosome abnormalities

Genetics

Norrie disease is usually inherited in an:

X-linked recessive pattern

The causative gene is:

NDP

located at:

Xp11.3–p11.4

NDP encodes:

Norrin

Norrin Signaling

Norrin participates in signaling through:

• FZD4
• LRP5
• TSPAN12
• β-catenin pathway

This pathway is essential for normal vascular development of the:

• Retina
• Inner ear

Abnormal signaling leads to defective retinal vascularization and retinal dysplasia.

NDP-Related Retinopathy Spectrum

Pathogenic variants in NDP can produce a spectrum ranging from:

• Classic severe Norrie disease
• Familial exudative vitreoretinopathy-like disease
• Less severe peripheral retinal vascular abnormalities

Phenotypic severity can therefore vary considerably.

Female Carriers

Most female carriers are asymptomatic.

However, some may show:

• Peripheral retinal avascularity
• Abnormal retinal vessels
• Pigmentary retinal changes
• Retinal folds
• Macular dragging
• Rare retinal detachment

These manifestations usually result from skewed X-inactivation.

Genetic Counseling

Carrier testing should be offered to appropriate female relatives.

If the familial NDP pathogenic variant is known, options may include:

• Prenatal genetic diagnosis
• Chorionic villus sampling
• Amniocentesis
• Preimplantation genetic testing

An affected male transmits the pathogenic variant to:

• All daughters
• No sons

A heterozygous carrier female has a:

• 50% chance of transmitting the variant to each child

Pathophysiology

The primary defect is abnormal retinal vascular development.

This results in:

• Peripheral retinal nonperfusion
• Retinal ischemia
• Fibrovascular proliferation
• Traction
• Retinal folds
• Retinal detachment
• Retinal dysplasia

Advanced cases develop a dense retrolental fibrovascular mass.

Pseudoglioma

The classic ophthalmoscopic appearance is a:

Yellow-gray or white retrolental mass

This is called a pseudoglioma because it can mimic retinoblastoma clinically.

The mass consists primarily of:

• Dysplastic retina
• Fibrovascular tissue
• Gliosis
• Detached retinal tissue

Associated Systemic Manifestations

Hearing Loss

Progressive sensorineural hearing loss is one of the major systemic features.

It often:

• Develops later in childhood or adolescence
• Progresses gradually
• Can become severe

Early childhood hearing may initially be normal.

Neurodevelopmental Features

Some affected patients develop:

• Developmental delay
• Intellectual disability
• Behavioral problems
• Psychiatric manifestations

These are variable and not universal.

Diagnosis

Diagnosis is based on:

• Bilateral congenital or early retinal disease
• Typical family history
• Characteristic ocular findings
• Molecular confirmation of an NDP pathogenic variant

History

Important history includes:

• Severe visual impairment from birth
• Poor fixation
• Nystagmus
• Leukocoria
• Family history of affected males
• Maternal relatives with unexplained blindness
• Hearing difficulty
• Developmental delay
• Behavioral abnormalities

Ophthalmic Examination

Visual Function

Visual function varies with severity.

Classic disease often results in:

• Light perception
• Hand-motion vision
• No useful vision

Milder disease can retain more functional vision.

Leukocoria

A retrolental fibrovascular mass may produce:

Leukocoria

This is an important presentation because retinoblastoma must be urgently excluded.

Retrolental Mass

The classic lesion is:

• Yellow-gray
• Elevated
• Fibrovascular
• Located behind the lens

The lens may initially remain clear.

Retinal Findings

Possible findings include:

• Retinal dysplasia
• Retinal folds
• Peripheral retinal avascularity
• Abnormal retinal vessels
• Tractional retinal detachment
• Total retinal detachment
• Pigmentary retinal changes

Disease is usually:

• Bilateral
• Approximately symmetric

Vitreous Findings

Possible findings include:

• Vitreous hemorrhage
• Fibrovascular proliferation
• Tractional bands

Anterior Segment Findings

With progression, eyes may develop:

• Iris atrophy
• Posterior synechiae
• Cataract
• Corneal opacity
• Shallow anterior chamber
• Secondary angle closure
• Elevated IOP

Nystagmus and Strabismus

Severe congenital visual impairment may produce:

• Sensory nystagmus
• Strabismus

These reflect profound early visual deprivation.

Diagnostic Testing

Molecular Genetic Testing

Testing for pathogenic variants in:

NDP

can confirm the diagnosis.

A negative test does not always completely exclude an NDP-related disorder because some variants may be difficult to detect depending on the testing method.

Examination of Female Relatives

The mother and other potential carriers may benefit from retinal examination looking for:

• Peripheral avascular retina
• Retinal vascular anomalies
• Pigmentary changes
• Macular dragging
• Retinal folds

Wide-field imaging may be helpful.

B-Scan Ultrasonography

B-scan is useful when the fundus cannot be visualized.

It may demonstrate:

• Retinal detachment
• Retrolental tissue
• Vitreous abnormalities
• Globe configuration

Importantly, a solid calcified intraocular mass strongly suggests retinoblastoma rather than Norrie disease.

Wide-Field Retinal Imaging

In milder disease, wide-field imaging can identify:

• Peripheral nonperfusion
• Vascular abnormalities
• Exudation
• Traction

Fluorescein Angiography

FA may demonstrate:

• Peripheral avascular retina
• Abnormal terminal vessels
• Leakage
• Neovascularization
• Areas of nonperfusion

It is particularly useful when considering treatment of incompletely vascularized retina.

OCT

OCT may be helpful in milder cases to assess:

• Macular architecture
• Retinal folds
• Traction
• Macular dragging

In severe advanced disease, imaging may be limited.

Audiologic Evaluation

Because hearing loss may develop later, patients require:

• Baseline audiology
• Regular hearing surveillance

Assessment may include:

• Pure-tone audiometry
• Auditory brainstem response in young children

Developmental Assessment

Early developmental evaluation should be considered if there are:

• Delayed milestones
• Language delay
• Learning difficulties
• Behavioral concerns

Pathology

Histopathologic findings may include:

• Dysplastic retinal architecture
• Fibrovascular proliferation
• Gliosis
• Retinal detachment
• Abnormal dilated retinal vessels
• Disorganized retinal layers

Differential Diagnosis

Important differential diagnoses include:

• Retinoblastoma
• Persistent fetal vasculature
• Familial exudative vitreoretinopathy
• Retinopathy of prematurity
• Coats disease
• Incontinentia pigmenti
• Isolated retinal dysplasia
• Syndromic retinal dysplasia
• Osteoporosis-pseudoglioma syndrome
• Traumatic retinal detachment

Critical Differential – Retinoblastoma

The most important diagnosis to exclude in an infant with leukocoria or a retrolental mass is:

Retinoblastoma

Features favoring retinoblastoma include:

• Intraocular tumor mass
• Calcification on ultrasonography or CT
• Typical retinal tumor morphology

Norrie disease more typically demonstrates:

• Bilateral retinal dysplasia
• Retinal detachment
• Fibrovascular pseudoglioma
• No calcified tumor

Persistent Fetal Vasculature

PFV usually:

• Is unilateral
• Occurs in a microphthalmic eye
• Shows a fibrovascular stalk extending from optic disc toward the posterior lens

Norrie disease is generally:

• Bilateral
• Symmetric
• Associated with widespread retinal dysplasia

Familial Exudative Vitreoretinopathy

FEVR and Norrie disease share abnormalities of retinal vascular development.

FEVR is often:

• Less severe
• More variable
• Associated with peripheral retinal avascularity
• Compatible with useful vision in some cases

NDP variants can themselves cause an FEVR-like phenotype.

Retinopathy of Prematurity

ROP is distinguished by:

• Prematurity
• Low birth weight
• Supplemental oxygen history
• Characteristic staged peripheral retinal vascular disease

Coats Disease

Coats disease is typically:

• Unilateral
• Male predominant
• Characterized by retinal telangiectasia and exudation

rather than bilateral congenital retinal dysplasia.

Treatment

There is currently no established therapy that corrects the underlying NDP mutation or restores a severely dysplastic retina.

Treatment depends strongly on:

• Age at diagnosis
• Amount of attached retina
• Degree of vascularization
• Presence of traction
• Visual potential

Early Disease

Patients diagnosed before total retinal detachment may benefit from early retinal treatment.

Options include:

• Laser photocoagulation
• Cryotherapy in selected cases
• Vitreoretinal surgery
• Combination approaches

The goal is to:

• Reduce ischemic drive
• Treat avascular retina
• Limit fibrovascular proliferation
• Preserve remaining attached retina

Laser Photocoagulation

Laser may be directed toward:

• Peripheral avascular retina
• Abnormal vascular junctions

especially when there is:

• Active neovascularization
• Exudation
• Progressive traction

Early treatment may preserve significantly more vision in milder phenotypes.

Vitreoretinal Surgery

Surgery may be considered for:

• Progressive retinal traction
• Retinal folds
• Partial retinal detachment
• Tractional retinal detachment

Procedures may include:

• Pars plana vitrectomy
• Membrane dissection
• Release of vitreoretinal traction
• Endolaser

Outcomes are much poorer when there is longstanding total retinal detachment and severe dysplasia.

Anti-VEGF Therapy

Anti-VEGF treatment has been used in selected NDP-related retinal vascular disorders as an adjunct to surgery or laser.

However:

• Evidence is limited
• It does not correct the underlying developmental defect
• Severe fibrovascular contraction is a theoretical concern

Therefore, anti-VEGF therapy should be individualized by a pediatric retina specialist rather than considered standard monotherapy.

Glaucoma Treatment

Secondary glaucoma may occur because of:

• Shallow anterior chamber
• Peripheral anterior synechiae
• Angle closure
• Severe anterior segment distortion

Treatment may include:

• Topical IOP-lowering therapy
• Lens extraction in selected cases
• Peripheral iridotomy or iridectomy when anatomically appropriate
• Trabeculectomy
• Glaucoma drainage device
• Cyclodestructive procedures

Cataract

Visually significant cataract may require surgery in selected eyes with useful retinal potential.

In eyes with extremely poor visual potential, intervention is primarily directed toward comfort.

Painful Blind Eye

Advanced eyes may develop:

• Chronic glaucoma
• Corneal decompensation
• Phthisis
• Persistent pain

Management may include:

• Cycloplegia
• Topical corticosteroid
• IOP-lowering therapy
• Cyclodestructive procedures

If pain remains uncontrolled:

• Enucleation
• Evisceration

may rarely be necessary.

Phthisis Bulbi

Severely affected eyes may progressively become:

• Small
• Disorganized
• Hypotonous

forming phthisis bulbi.

Prosthetic and Orbital Rehabilitation

In a blind, severely microphthalmic or phthisical eye, options may include:

• Cosmetic shell
• Ocular prosthesis
• Orbital conformer in selected children

These can improve:

• Cosmesis
• Symmetry
• Orbital growth

Hearing Rehabilitation

Patients with hearing loss may benefit from:

• Hearing aids
• Assistive listening devices
• Cochlear implantation in severe disease

Early identification is especially important because concurrent visual impairment makes auditory communication critical.

Low-Vision and Blindness Services

Early referral should include:

• Low-vision services
• Orientation and mobility training
• Braille or alternative educational support
• Visual rehabilitation
• Occupational therapy

Developmental and Behavioral Support

Children may require:

• Early developmental intervention
• Speech and language therapy
• Behavioral therapy
• Educational accommodations
• Psychiatric assessment when indicated

Multidisciplinary Care

Management may involve:

• Pediatric ophthalmology
• Retina specialist
• Glaucoma specialist
• Medical genetics
• Audiology
• ENT
• Developmental pediatrics
• Neurology
• Behavioral health
• Low-vision services

Follow-Up

Regular ophthalmic examination is needed to monitor for:

• Progressive retinal detachment
• Fibrovascular proliferation
• Cataract
• Glaucoma
• Corneal complications
• Phthisis

Milder phenotypes require particularly careful retinal surveillance because useful vision may still be preservable.

Audiologic Follow-Up

Hearing should be monitored longitudinally even when normal in early childhood because:

Sensorineural hearing loss may develop later.

Patient and Family Education

Families should understand:

• The X-linked inheritance pattern
• Importance of genetic counseling
• Need for ophthalmic surveillance
• Possibility of progressive hearing loss
• Importance of developmental support
• Limited visual prognosis in classic severe disease

Prognosis

Visual Prognosis

Classic Norrie disease has a poor visual prognosis.

Many affected males have:

• Severe bilateral retinal detachment at birth or infancy
• Profound visual impairment
• Hand-motion vision or less

Earlier recognition of milder disease may allow treatment that preserves more useful vision.

Hearing Prognosis

Hearing can be normal during early childhood but may progressively decline.

Regular audiologic surveillance is therefore essential.

Systemic Prognosis

Life expectancy may be relatively normal in many patients, but quality of life depends heavily on:

• Visual disability
• Hearing impairment
• Developmental difficulties
• Behavioral complications

Complications

Important ocular complications include:

• Tractional retinal detachment
• Total retinal detachment
• Vitreous hemorrhage
• Cataract
• Secondary glaucoma
• Corneal opacity
• Phthisis bulbi
• Painful blind eye

Systemic complications include:

• Progressive sensorineural hearing loss
• Developmental delay
• Behavioral or psychiatric disorders

Ophthalmology Pearls

• Norrie disease is an X-linked recessive retinal dysplasia caused by pathogenic variants in NDP.
• The classic patient is a male infant with bilateral severe visual loss, retinal dysplasia, and retrolental pseudogliomas.
• Norrin signaling is essential for normal retinal and inner-ear vascular development.
• The most important differential diagnosis for a retrolental mass or leukocoria is retinoblastoma.
• Absence of tumor calcification and bilateral retinal dysplasia favor Norrie disease over retinoblastoma.
• Norrie disease and FEVR belong to an overlapping retinal vascular-development spectrum.
• Female carriers are usually unaffected but may have peripheral vascular or pigmentary retinal abnormalities.
• If substantial retina remains attached, early laser and/or vitreoretinal surgery may preserve vision.
• Advanced total retinal detachment has a poor visual prognosis.
• Progressive sensorineural hearing loss may develop later, so normal hearing in infancy does not eliminate the need for surveillance.
• Long-term care should include ophthalmology, genetics, audiology, developmental support, and low-vision rehabilitation.

Ophthalmology – Normal-Tension Glaucoma

Basics

Description

Normal-tension glaucoma (NTG) is a form of primary open-angle glaucoma in which characteristic glaucomatous optic nerve damage and visual field loss occur despite measured intraocular pressure (IOP) remaining within the statistically normal range.

Typical features include:

• Open anterior chamber angles
• Glaucomatous optic nerve cupping
• Retinal nerve fiber layer loss
• Corresponding visual field defects
• No consistently documented untreated IOP above the normal statistical range

NTG is therefore a diagnosis of exclusion.

Important Concept

A “normal” IOP does not mean the pressure is safe for that particular optic nerve.

Some optic nerves may be damaged at relatively low IOPs because of:

• Structural susceptibility
• Vascular dysregulation
• Reduced ocular perfusion
• Thin corneas causing IOP underestimation
• Nocturnal or undetected IOP peaks

Epidemiology

The prevalence varies greatly between populations because of differences in:

• Diagnostic criteria
• IOP measurement methods
• Visual field definitions
• Population characteristics

NTG constitutes a substantial proportion of open-angle glaucoma, particularly in some Asian populations.

It is likely underdiagnosed because IOP may appear “normal” during routine examination.

Risk Factors

Important associated risk factors include:

• Increasing age
• Family history of glaucoma
• Female sex in some studies
• Migraine
• Raynaud phenomenon
• Obstructive sleep apnea
• Systemic hypotension
• Nocturnal blood pressure dipping
• Vascular dysregulation
• Thin central cornea
• Disc hemorrhage

Genetics

NTG is genetically heterogeneous.

Reported genes and loci include:

• OPTN – optineurin
• TBK1 in selected familial cases
• Other glaucoma-associated loci

Most cases are multifactorial rather than caused by a single mutation.

Genetic testing is not routinely required for typical NTG.

Pathophysiology

The final pathway is:

Retinal ganglion cell loss → optic nerve axonal loss → visual field loss

Multiple mechanisms likely contribute.

Role of Intraocular Pressure

Although IOP is within the statistically normal range, it remains the most important modifiable risk factor.

The Collaborative Normal-Tension Glaucoma Study demonstrated that approximately:

30% reduction from baseline IOP

reduces the risk of disease progression in many patients.

Thus:

NTG is not an IOP-independent disease.

Mechanical Mechanisms

Even “normal” levels of IOP may produce damage in a susceptible optic nerve.

Possible mechanisms include:

• Lamina cribrosa deformation
• Impaired axoplasmic transport
• Structural weakness of the optic nerve head
• Reduced tolerance to translaminar pressure gradients

Vascular Mechanisms

Vascular factors may contribute through inadequate optic nerve perfusion.

Potential mechanisms include:

• Low systemic blood pressure
• Excessive nocturnal hypotension
• Vascular dysregulation
• Vasospasm
• Migraine-related vascular instability
• Sleep apnea-associated nocturnal hypoxia

Ocular Perfusion Pressure

A simplified concept is:

Ocular perfusion pressure ≈ blood pressure − IOP

Therefore, optic nerve perfusion may fall because of:

• Increased IOP
• Reduced systemic blood pressure
• Both occurring simultaneously

This may be particularly relevant at night.

Associated Conditions

Common associations include:

• Migraine
• Raynaud phenomenon
• Obstructive sleep apnea
• Systemic hypotension
• Peripheral vascular dysregulation

These associations are not present in all patients.

Diagnosis

NTG should only be diagnosed after demonstrating:

• Typical glaucomatous structural damage
• Corresponding functional loss
• Open angles
• No convincing history of significantly elevated IOP
• No better explanation for the optic neuropathy

History

Important questions include:

• Visual symptoms
• Family history of glaucoma
• Previous IOP measurements
• Previous steroid use
• Ocular trauma
• Prior ocular surgery
• Migraine
• Raynaud symptoms
• Sleep apnea symptoms
• Snoring
• Daytime somnolence
• Systemic hypertension
• Antihypertensive medication timing
• Episodes of severe hypotension
• Blood loss or shock
• Neurologic symptoms

Visual Symptoms

Early disease is often asymptomatic.

Later symptoms may include:

• Difficulty with contrast
• Paracentral blur
• Reading difficulty
• Reduced peripheral vision

Central vision may remain good until advanced disease.

Pupillary Examination

A relative afferent pupillary defect may occur when damage is significantly asymmetric.

Slit-Lamp Examination

Look for signs suggesting secondary glaucoma, including:

• Pseudoexfoliation material
• Pigment dispersion
• Prior inflammation
• Iris transillumination defects
• Previous trauma or surgery
• Steroid-related changes

Gonioscopy

Gonioscopy is essential.

Typical NTG shows:

Open angles without a secondary cause of glaucoma

Gonioscopy also helps exclude:

• Angle closure
• Neovascularization
• Pigment dispersion
• Recession
• Inflammatory synechiae

Central Corneal Thickness

Pachymetry should be obtained.

A thin central cornea may:

• Cause Goldmann applanation IOP to underestimate true pressure
• Independently correlate with glaucoma risk

Therefore, an apparently low IOP should be interpreted in context.

Optic Nerve Findings

Typical glaucomatous findings include:

• Neuroretinal rim thinning
• Focal notching
• Vertical cup enlargement
• Cup-to-disc asymmetry
• RNFL defects
• Acquired optic nerve pits
• Disc hemorrhage
• Parapapillary atrophy

Disc Hemorrhage

Optic disc hemorrhage is particularly important in NTG.

It is associated with:

• Active disease
• Higher risk of progression
• Subsequent localized RNFL loss

A disc hemorrhage should prompt reassessment of:

• Target IOP
• Adherence
• Rate of progression

Neuroretinal Rim

Damage often preferentially involves the:

• Inferotemporal rim
• Superotemporal rim

This corresponds to characteristic arcuate visual field loss.

Optic Disc Pallor

Glaucoma causes cupping that is generally greater than pallor.

Marked pallor out of proportion to cupping should raise suspicion for another optic neuropathy.

Visual Field Findings

NTG may produce:

• Paracentral scotomas
• Nasal steps
• Arcuate defects
• Altitudinal-like defects
• Advanced generalized field constriction

Paracentral defects may occur relatively early and can threaten fixation.

Central Visual Field Testing

Because NTG can produce defects close to fixation, consider:

• Standard 24-2 or 24-2C testing
• 10-2 visual fields when central or paracentral damage is suspected

This can detect defects missed or underestimated by wider-spaced field strategies.

Optical Coherence Tomography

OCT is essential for documenting:

• RNFL thickness
• Macular ganglion cell complex
• Ganglion cell–inner plexiform layer
• Progressive structural loss

Macular OCT is particularly valuable when paracentral field loss is suspected.

Optic Disc Photography

Baseline and serial stereoscopic disc photography can document:

• Progressive rim thinning
• Disc hemorrhage
• RNFL changes

IOP Assessment

Single office IOP readings may miss clinically relevant pressure peaks.

Consider:

• Repeated measurements
• Measurements at different times of day
• Diurnal testing in selected patients

A patient classified as NTG may occasionally be found to have previously unrecognized pressure spikes.

Laboratory Testing

There is no routine laboratory test for NTG.

Testing should be guided by suspected associated or alternative disease.

For example:

• CBC if severe anemia is suspected
• ESR/CRP if arteritic ischemic optic neuropathy is a concern
• Other investigations based on systemic findings

When to Consider Neuroimaging

MRI of the brain and orbits should be considered when findings are atypical for glaucoma.

Red flags include:

• Young age
• Rapid progression
• Markedly asymmetric or unilateral disease
• Central visual acuity loss out of proportion to glaucoma
• Central scotoma
• Color vision loss disproportionate to field damage
• Neurologic symptoms
• Hemianopic field defect
• Optic disc pallor greater than cupping
• Unusual visual field pattern

Differential Diagnosis

Important mimics include:

• Compressive optic neuropathy
• Optic neuritis
• Non-arteritic anterior ischemic optic neuropathy
• Arteritic ischemic optic neuropathy
• Dominant optic atrophy
• Leber hereditary optic neuropathy
• Traumatic optic neuropathy
• Toxic or nutritional optic neuropathy
• Congenital optic nerve anomalies
• Optic nerve coloboma
• Optic disc pits
• Tilted disc syndrome

Previously Elevated IOP

Before labeling a patient as NTG, exclude previous periods of elevated IOP from:

• Steroid use
• Trauma
• Uveitis
• Ocular surgery
• Pigment dispersion
• Pseudoexfoliation
• Intermittent angle closure

Treatment Goals

The goal is to reduce IOP sufficiently to slow disease progression to a rate compatible with useful lifetime vision.

The target pressure is individualized according to:

• Baseline IOP
• Age
• Life expectancy
• Visual field status
• Rate of progression
• Central field involvement
• Fellow-eye status
• Treatment burden

Target IOP

A common initial target is approximately:

30% below untreated baseline IOP

based on the Collaborative Normal-Tension Glaucoma Study.

However, target IOP is dynamic and should be adjusted according to progression.

Observation

Not every untreated patient progresses rapidly.

Observation may be reasonable in selected patients with:

• Minimal damage
• No documented progression
• Advanced age
• Significant treatment burden

However, close structural and functional monitoring is essential.

Medical Therapy

Prostaglandin Analogs

Common first-line agents include:

• Latanoprost
• Travoprost
• Bimatoprost
• Tafluprost

Advantages include:

• Strong IOP lowering
• Once-daily dosing
• Minimal systemic cardiovascular effects

Rho Kinase Inhibitors

Agents such as:

• Netarsudil

may be useful as additional therapy, particularly when further IOP reduction is required.

Carbonic Anhydrase Inhibitors

Topical options include:

• Dorzolamide
• Brinzolamide

They may be used alone or in combination.

Alpha-2 Agonists

Brimonidine lowers IOP and is commonly used as adjunctive therapy.

Experimental neuroprotective effects have been proposed, but independent human neuroprotection remains unproven.

Beta-Blockers

Topical beta-blockers such as:

• Timolol

can effectively reduce IOP.

Use cautiously in patients with:

• Asthma
• Bradycardia
• Heart block
• Significant nocturnal hypotension

Because systemic blood pressure and optic nerve perfusion may be relevant in NTG, medication choice and timing should be individualized.

Miotics

Pilocarpine can lower IOP but is now used much less commonly because of:

• Frequent dosing
• Brow ache
• Induced myopia
• Reduced quality of life
• Retinal detachment considerations in susceptible eyes

Oral Carbonic Anhydrase Inhibitors

Agents such as:

• Acetazolamide
• Methazolamide

may be used temporarily in selected cases but are generally not suitable for long-term routine therapy because of systemic adverse effects.

Selective Laser Trabeculoplasty

SLT is an effective treatment option for NTG.

It may be used:

• As primary therapy
• As adjunctive therapy

Because baseline IOP is already relatively low, the absolute pressure reduction may be smaller than in high-pressure glaucoma.

Nevertheless, even modest additional IOP lowering can be clinically meaningful.

Filtering Surgery

When progression continues despite maximally tolerated medical or laser therapy, surgery may be required.

Options include:

• Trabeculectomy
• Glaucoma drainage device in selected circumstances

Trabeculectomy in NTG

Trabeculectomy can achieve very low IOP levels and is often the most effective surgical method when a very low target is required.

However, NTG patients have a relatively narrow therapeutic window between:

• Desired low IOP
• Excessive hypotony

Therefore, careful postoperative management is essential.

Hypotony Risk

Potential complications include:

• Hypotony
• Hypotony maculopathy
• Choroidal effusion
• Shallow anterior chamber

This is particularly relevant when very low postoperative IOP is sought.

Minimally Invasive Glaucoma Surgery

MIGS may provide useful IOP reduction in selected patients, especially when combined with cataract surgery.

However, angle-based MIGS is limited by:

Episcleral venous pressure

and may not achieve the very low target pressures required in advanced or rapidly progressive NTG.

Tube Shunts

Glaucoma drainage devices may be considered when:

• Trabeculectomy is unsuitable
• Previous filtration surgery has failed
• Conjunctival scarring is significant

They are not necessarily the first surgical choice when extremely low IOP is required.

Cyclodestructive Procedures

Cyclophotocoagulation is generally reserved for:

• Refractory glaucoma
• Eyes with limited visual potential
• Selected surgical circumstances

It is not usually first-line treatment for typical NTG.

Systemic Vascular Considerations

Management should also address potentially relevant systemic factors.

Consider evaluation for:

• Obstructive sleep apnea
• Significant nocturnal hypotension
• Severe anemia
• Cardiovascular disease

Nocturnal Hypotension

In patients who progress despite low IOP, ask whether antihypertensive medications are taken at bedtime.

Excessive overnight blood pressure reduction may potentially reduce optic nerve perfusion.

However:

Antihypertensive therapy should not be stopped or changed without coordination with the treating physician.

Sleep Apnea

Patients with:

• Loud snoring
• Witnessed apneas
• Daytime somnolence
• Morning headaches

should be considered for evaluation of obstructive sleep apnea.

Neuroprotection

Many neuroprotective strategies have been investigated.

At present:

No IOP-independent neuroprotective medication has been definitively proven to prevent glaucomatous progression in routine clinical practice.

Effective IOP lowering remains the main evidence-based treatment.

Referral

Consider neuro-ophthalmology referral when:

• The diagnosis is uncertain
• Visual loss is atypical
• Pallor exceeds cupping
• Visual fields suggest neurologic disease
• Progression is unusually rapid

Low-vision referral is appropriate when visual disability affects daily function.

Follow-Up

After starting or changing treatment, reassess:

• IOP response
• Medication tolerance
• Adherence

High-risk patients may require early review.

Once stable, follow-up is commonly every:

3–6 months

depending on disease severity and progression.

Monitoring

Long-term monitoring should include:

• IOP
• Optic nerve examination
• Disc photographs
• OCT RNFL
• Macular ganglion cell analysis
• Standard automated perimetry
• 10-2 fields when central damage is present

Rate of Progression

The most important long-term question is:

How fast is the disease progressing?

A young patient with slow progression may still accumulate major lifetime visual loss, whereas an older patient with stable mild damage may require less aggressive treatment.

Patient Education

Patients should understand that:

• Normal-range IOP does not exclude glaucoma.
• Treatment still focuses on lowering pressure.
• Medication adherence is essential.
• Regular visual fields and OCT are necessary.
• Progression can occur even without symptoms.

Prognosis

Prognosis depends primarily on:

• Age
• Baseline damage
• Rate of progression
• Presence of central field defects
• Ability to reduce IOP
• Adherence to follow-up

Many patients maintain useful vision throughout life when progression is recognized early and adequately slowed.

Fellow Eye

Patients with unilateral or asymmetric NTG remain at risk for development or progression of glaucomatous damage in the fellow eye.

Both eyes require continued surveillance.

Complications

Untreated or inadequately controlled disease can cause:

• Progressive visual field loss
• Paracentral scotoma
• Fixation-threatening defects
• Severe peripheral field loss
• Permanent visual impairment
• Blindness in advanced disease

Treatment-related complications include:

• Medication adverse effects
• Laser-related inflammation or pressure spikes
• Surgical hypotony
• Infection
• Filtration failure

Ophthalmology Pearls

• NTG = glaucomatous optic neuropathy with open angles and IOP that remains within the statistically normal range.
• NTG is a diagnosis of exclusion; do not assume every cupped optic nerve with normal IOP is glaucoma.
• A “normal” IOP may still be too high for an individual optic nerve.
• Disc hemorrhage is an important marker of progression, especially in NTG.
• NTG commonly produces paracentral visual field defects, so 10-2 testing can be valuable.
• Thin corneas may cause measured IOP to underestimate the true pressure.
• The Collaborative Normal-Tension Glaucoma Study supports an initial target of roughly 30% IOP reduction from baseline in patients requiring treatment.
• SLT remains useful, although the absolute IOP reduction may be smaller because baseline pressure is already low.
• Trabeculectomy may be required to reach very low target pressures, but hypotony is an important risk.
• Migraine, Raynaud phenomenon, sleep apnea, and excessive nocturnal hypotension may be relevant systemic associations.
• Marked optic disc pallor, rapid progression, central acuity loss, or neurologically patterned field defects should prompt neuroimaging rather than automatic labeling as NTG.
• IOP reduction remains the only established treatment proven to slow glaucomatous progression.

Ophthalmology – Non-Physiologic Vision Loss

Basics

Description

Non-physiologic vision loss refers to visual symptoms that are not fully explained by identifiable ocular or neurologic disease.

Modern preferred terms include:

• Functional vision disorder
• Functional visual loss
• Non-organic visual loss

Older terms such as “hysterical” or “psychosomatic” are generally avoided.

Symptoms may arise in different contexts:

• Functional neurologic/psychogenic symptoms – symptoms are experienced as genuine and are not consciously produced
• Factitious disorder – symptoms are intentionally produced to assume a sick role
• Malingering – symptoms are intentionally produced for external gain

A functional component can also coexist with true organic disease.

⸻

Epidemiology

Functional visual symptoms account for a small but important proportion of ophthalmic presentations.

Reported prevalence is approximately:

1–5% of patients presenting with visual complaints

It is seen particularly in:

• Children
• Adolescents
• Young adults

Functional symptoms are common in children and younger adults.

Historically, malingering has been reported more often in adults.

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Risk Factors and Associations

Potential associated factors include:

• Psychological stress
• Family or school conflict
• Anxiety
• Depression
• Trauma
• Major life changes
• Secondary gain
• Psychiatric illness
• Functional neurologic disorder

However:

The absence of an obvious psychological stressor does not exclude functional vision disorder.

⸻

Associated Psychiatric Conditions

Some patients have coexisting psychiatric conditions, including:

• Anxiety disorders
• Depression
• Somatic symptom disorder
• Functional neurologic disorder
• Illness anxiety disorder
• Body dysmorphic disorder

Not every patient has a diagnosable psychiatric disorder.

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Pathophysiology

There is no structural lesion that adequately explains the visual deficit.

Symptoms may affect:

• Visual acuity
• Visual fields
• Ocular motility
• Accommodation
• Pupillary function
• Eyelid position
• Sensation

The modern understanding of functional neurologic symptoms emphasizes abnormal brain network function rather than deliberate symptom production.

⸻

Possible Manifestations

Functional visual symptoms may include:

• Monocular or binocular visual loss
• Visual field constriction
• Central scotoma
• Diplopia
• Abnormal eye movements
• Spasm of the near reflex
• Functional ptosis
• Blepharospasm
• Altered facial or corneal sensation

⸻

Diagnosis

The diagnosis should be based on positive examination findings showing internal inconsistency or preserved visual function, not simply on the absence of identifiable disease.

Before diagnosing functional visual loss, important organic causes must be excluded.

⸻

History

Important questions include:

• Exact nature of visual symptoms
• Onset and duration
• Monocular versus binocular involvement
• Degree of functional disability
• Variability of symptoms
• Situational triggers
• School, work, or family stressors
• Associated neurologic symptoms
• Previous ocular or neurologic disease
• Medications
• Psychiatric history
• Potential external incentives

Observe:

• Affect
• Behavior
• Consistency between reported disability and observed function

⸻

Important Clinical Principle

A patient’s emotional response to visual loss is not diagnostic.

Some patients with severe organic disease may appear unconcerned, while some patients with functional symptoms may be extremely distressed.

Diagnosis must rest on objective examination findings.

⸻

Physical Examination

A complete ophthalmic examination should include:

• Best-corrected visual acuity
• Pupillary examination
• Color vision
• Ocular motility
• Alignment
• Slit-lamp examination
• Dilated fundus examination
• Visual fields

Look carefully for subtle organic disease.

⸻

Functional Visual Acuity Loss

Visual acuity may appear dramatically reduced despite preserved visual behavior.

Possible patterns include:

• Similar acuity at different testing distances
• Better near than expected from distance acuity
• Improved performance when testing is altered or distraction is introduced
• Inconsistent responses during repeated testing

⸻

Testing Visual Acuity

Start With the Smallest Line

Instead of beginning with large letters, start near the expected acuity level.

This may reveal unexpectedly good performance before the patient anticipates the test strategy.

⸻

Near Visual Acuity

Near acuity may be disproportionately better than distance acuity.

For example:

• Severe claimed distance loss
• Relatively preserved reading ability

This discrepancy can support a functional component.

⸻

Fogging Techniques

In suspected unilateral functional loss, the “good” eye can be blurred or fogged while binocular acuity is tested.

If the patient continues to read well, the supposedly poor eye must be contributing vision.

This is one of the most useful objective techniques.

⸻

Prism Dissociation Test

A prism placed before one eye may produce two images if both eyes are seeing.

This can demonstrate preserved vision in an eye claimed to be profoundly impaired.

⸻

Stereopsis

Preserved stereopsis provides evidence that both eyes have useful vision.

The degree of stereopsis can estimate a minimum level of binocular visual function.

⸻

Optokinetic Nystagmus

An optokinetic drum or strip can elicit reflexive eye movements.

Presence of optokinetic nystagmus suggests at least moderate visual function.

It is useful particularly when cooperation is limited.

⸻

Mirror Test

A large mirror can be moved or tilted in front of the patient.

Patients with useful vision often reflexively track their reflected image.

This test is particularly useful in young children.

⸻

Menace and Navigation

Observe spontaneous behavior such as:

• Avoiding obstacles
• Reaching accurately for objects
• Navigating through the room
• Looking toward visual stimuli

Functional behavior inconsistent with claimed profound blindness is diagnostically useful.

⸻

Visual Field Loss

The most common functional visual field pattern is:

Concentric constriction

sometimes described as:

• Tunnel vision
• Tubular visual field

⸻

Tubular Visual Field

In true physiologic visual field constriction, the field should enlarge as testing distance increases.

In functional visual loss, the patient may report essentially the same field diameter at:

• 1 meter
• 2 meters
• Greater distances

This produces a geometrically impossible “tubular” field.

⸻

Tangent Screen Testing

Tangent screen testing can demonstrate:

• Nonexpanding visual field with increased testing distance
• Inconsistent field boundaries

These findings strongly support a nonphysiologic pattern.

⸻

Goldmann Perimetry

Possible functional findings include:

• Crossing isopters
• Spiraling isopters
• Inconsistent field size
• Marked variability during the same examination

These findings should be interpreted cautiously because poor attention can also cause inconsistent fields.

⸻

Automated Perimetry

Automated fields may show:

• Poor reproducibility
• Cloverleaf patterns
• High false-negative responses
• Implausible defects

However:

An unreliable automated field is not by itself diagnostic of functional visual loss.

⸻

Monocular Hemianopia

A monocular hemianopic defect that respects the vertical meridian is anatomically implausible because postchiasmal lesions cause homonymous defects involving corresponding halves of both eyes.

Such patterns may suggest functional loss.

⸻

Monocular Diplopia

Functional diplopia may be suspected when:

• Diplopia persists after occlusion of the other eye
• Refraction, corneal, lenticular, and retinal causes are excluded
• Images have unusual or inconsistent separation

However, organic monocular diplopia must first be excluded.

⸻

Ocular Motility Abnormalities

Functional ocular motor findings may include:

• Apparent horizontal gaze palsy
• Apparent vertical gaze palsy
• Convergence insufficiency
• Spasm of near reflex
• Voluntary nystagmus

⸻

Spasm of the Near Reflex

Characterized by episodic:

• Convergence
• Accommodation
• Miosis

This may mimic:

• Bilateral abduction weakness
• Sixth nerve palsy

The presence of pupillary constriction during apparent abduction limitation is an important clue.

⸻

Voluntary Nystagmus

Voluntary nystagmus is typically:

• High frequency
• Low amplitude
• Horizontal
• Sustained only briefly

It may be reproduced by some healthy individuals.

It can resemble:

• Ocular flutter
• Opsoclonus

but lacks associated neurologic disease.

⸻

Functional Ptosis

Features may include:

• Active orbicularis contraction
• Brow depression
• Variable eyelid position
• Improvement with distraction

True neurologic and myogenic ptosis must be excluded.

⸻

Pupils

A major clue to organic versus functional visual loss is the pupillary examination.

Profound unilateral optic nerve dysfunction should generally produce:

A relative afferent pupillary defect

If a patient claims severe unilateral visual loss with:

• Normal pupils
• No RAPD

then profound optic neuropathy or extensive retinal disease becomes less likely.

⸻

Sensory Symptoms

Functional sensory symptoms may include:

• Reduced corneal sensation
• Facial numbness
• Hypersensitivity

These may not respect known neuroanatomic distributions.

⸻

Objective Testing

Objective studies can be useful when the diagnosis remains uncertain.

⸻

Visual Evoked Potentials

Visual evoked potentials may demonstrate preserved cortical visual responses.

Limitations include:

• Variability
• Dependence on attention and fixation
• Poor specificity

A normal VEP can support preserved visual pathway function but does not prove malingering or a functional disorder.

⸻

Electroretinography

ERG may help exclude retinal disease.

Useful tests include:

• Full-field ERG
• Multifocal ERG

These may help identify subtle retinal disorders that can mimic functional visual loss.

⸻

Optical Coherence Tomography

OCT can help identify subtle:

• Macular disease
• Retinal nerve fiber layer loss
• Ganglion cell abnormalities
• Optic neuropathy

A structurally normal OCT supports—but does not by itself prove—a functional diagnosis.

⸻

Neuroimaging

MRI may be appropriate when:

• Visual loss is unexplained
• Field loss is reproducible
• There are neurologic signs
• Optic neuropathy or retrochiasmal disease is suspected

Imaging should be directed at the suspected anatomic pathway.

⸻

Functional Overlay

Functional visual symptoms can coexist with organic disease.

This is sometimes called:

Functional overlay

Examples include:

• Mild optic neuropathy with claimed complete blindness
• Small retinal lesion with disproportionately severe field loss
• True amblyopia with additional functional visual symptoms

Therefore:

Finding some organic disease does not exclude a functional component, and diagnosing functional symptoms does not eliminate the possibility of coexisting organic disease.

⸻

Differential Diagnosis

Always exclude subtle or early organic disease.

Important mimics include:

• Optic neuritis
• Ischemic optic neuropathy
• Leber hereditary optic neuropathy
• Compressive optic neuropathy
• Occipital lesions
• Migraine aura
• Occipital epilepsy
• Retinal dystrophies
• Macular dystrophies
• Acute zonal occult outer retinopathy
• Paraneoplastic retinopathy
• Paraneoplastic optic neuropathy
• Retinal toxicity
• Inflammatory retinal disease
• Cerebral infarction
• Intracranial mass

⸻

Important Diagnostic Principle

The diagnosis should preferably be made by demonstrating:

What the patient can see

rather than merely showing that no lesion was found.

Positive signs of preserved visual function are much more reassuring and diagnostically robust.

⸻

Functional Vision Disorder vs Malingering

These should not be considered synonymous.

Functional Vision Disorder

Symptoms are:

• Experienced as real
• Not consciously produced
• Often associated with stress or functional neurologic symptoms

Malingering

Symptoms are:

• Intentionally produced
• Motivated by external gain

Examples of external gain include:

• Financial compensation
• Avoiding work
• Legal advantage
• Obtaining drugs or services

⸻

Factitious Disorder

Factitious symptoms are intentionally produced, but the primary motivation is:

• Assuming the sick role

rather than obvious external reward.

⸻

Treatment

Reassurance

The mainstay of treatment for functional visual loss is:

Supportive, non-confrontational reassurance

Explain that:

• The examination shows that the visual pathways are functioning.
• No evidence of permanent ocular or neurologic damage has been identified.
• Recovery is expected.

⸻

Positive Explanation

A useful approach is to frame the diagnosis positively:

• “Your visual system is structurally healthy.”
• “The testing shows that your eyes can see better than the initial measurements suggested.”
• “This type of visual problem often improves.”

Avoid implying that symptoms are fabricated.

⸻

Avoid Confrontation

Do not accuse the patient of:

• Pretending
• Lying
• Seeking attention

Even when malingering is suspected, confrontation usually:

• Damages the therapeutic relationship
• Reduces cooperation
• Makes follow-up more difficult

⸻

Children

In children, treatment often consists of:

• Reassurance
• Reducing anxiety
• Normalizing activity
• School reintegration
• Family support

Most children improve without intensive intervention.

⸻

Psychological or Psychiatric Referral

Consider referral when:

• Symptoms persist
• Stressors are significant
• Anxiety or depression is suspected
• Functional neurologic symptoms are present
• There is major psychosocial dysfunction
• There is concern for self-harm

Referral should be presented supportively rather than as proof that symptoms are “imaginary.”

⸻

Psychotherapy

Psychotherapy may help selected patients, particularly when there is:

• Functional neurologic disorder
• Anxiety
• Trauma
• Depression
• Persistent symptoms

Approaches may include:

• Cognitive behavioral therapy
• Stress management
• Treatment of underlying psychiatric conditions

⸻

Safety Concerns

Urgent psychiatric or emergency referral is required when there is:

• Suicidal ideation
• Risk of self-harm
• Threats toward others
• Severe psychiatric decompensation

⸻

Follow-Up

Reevaluation is appropriate if symptoms:

• Persist
• Worsen
• Change pattern
• Become anatomically consistent with organic disease

Repeat examination is important because early organic disease may occasionally be subtle.

⸻

Prognosis

The prognosis is generally favorable.

More than half of patients improve or experience complete resolution.

Children often have particularly good recovery.

Recovery may occur:

• Rapidly
• Over several weeks
• Gradually over months

Persistent symptoms warrant reassessment for both:

• Functional contributors
• Previously occult organic disease

⸻

Ophthalmology Pearls

• Functional vision disorder is diagnosed by positive evidence of preserved visual function, not simply by a normal eye exam.
• Modern terminology favors functional visual loss / functional vision disorder rather than “hysterical” vision loss.
• Functional symptoms are not the same as malingering.
• Malingering involves intentional symptom production for external gain; functional symptoms are not consciously produced.
• A severe unilateral claimed visual loss with a normal pupillary examination and no RAPD should raise suspicion for a non-organic component.
• Useful tests include fogging, prism dissociation, stereopsis, optokinetic nystagmus, mirror testing, and observation of navigation.
• A tubular visual field that does not enlarge with increased testing distance is strongly nonphysiologic.
• Crossing or spiraling isopters can suggest functional field loss.
• Always exclude subtle organic disease such as optic neuritis, retinal dystrophy, LHON, macular disease, or cerebral pathology.
• Functional symptoms can coexist with true ocular disease—functional overlay is real and important.
• Management should be supportive and non-confrontational, with reassurance that the visual system is capable of normal function.
• Persistent or worsening symptoms require reevaluation rather than assuming the diagnosis is permanently settled.

Ophthalmology – Non-Granulomatous Anterior Uveitis

Basics

Description

Non-granulomatous anterior uveitis (NGAU) is inflammation predominantly involving the anterior uveal tract:

• Iris → iritis
• Ciliary body → cyclitis
• Both → iridocyclitis

Typical symptoms include:

• Ocular pain
• Redness
• Photophobia
• Blurred vision

It may be:

• Infectious
• Immune-mediated
• Associated with systemic disease
• Limited to the eye
• Idiopathic

A classic slit-lamp feature is the presence of small, fine keratic precipitates (KPs) rather than the large “mutton-fat” KPs more typical of granulomatous inflammation.

Epidemiology

Reported incidence is approximately:

8–17 cases per 100,000 population

Important epidemiologic associations include:

• HLA-B27-associated uveitis – more common in younger adults, classically males with spondyloarthropathy
• Behçet disease – more common in populations from the Middle East and parts of Asia
• JIA-associated uveitis – more common in children, particularly girls with certain JIA phenotypes

Risk Factors

Important risk factors include:

• Ocular trauma
• HLA-B27 positivity
• HLA-B51 positivity
• Autoimmune disease
• Smoking
• Previous episodes of uveitis
• Certain infections
• Selected medications

Genetics

HLA-B27

Associated with:

• Ankylosing spondylitis
• Reactive arthritis
• Psoriatic arthritis
• Inflammatory bowel disease-associated arthritis

HLA-B27-associated anterior uveitis is typically:

• Acute
• Unilateral
• Recurrent
• Painful
• Often associated with marked anterior chamber inflammation

HLA-B51

Associated particularly with:

Behçet disease

which may cause:

• Recurrent anterior uveitis
• Hypopyon
• Retinal vasculitis
• Panuveitis

Etiology

Common causes include:

• Idiopathic
• HLA-B27-associated disease
• JIA
• Herpetic anterior uveitis
• Fuchs uveitis syndrome
• Posner-Schlossman syndrome
• Behçet disease
• TINU syndrome
• Trauma
• Lens-induced inflammation
• UGH syndrome
• Drug-induced uveitis

A substantial proportion of cases remain idiopathic.

Classification by Clinical Course

Using standard uveitis terminology:

Acute

• Sudden onset
• Limited duration

Recurrent

• Repeated episodes
• Separated by periods of inactivity without treatment

Chronic

• Persistent inflammation
• Relapse soon after treatment is stopped

History

A targeted history is essential.

Ask about:

• Onset
• Duration
• Laterality
• Previous episodes
• Trauma
• Previous ocular surgery
• Previous treatment
• Response to corticosteroids
• Medication use
• Infectious exposures
• Autoimmune disease
• STI risk
• Intravenous drug use

Review of Systems

Constitutional

Ask about:

• Fever
• Chills
• Night sweats
• Weight loss

These may suggest:

• Infection
• Tuberculosis
• Malignancy
• Systemic inflammatory disease

Skin and Mucosal Symptoms

Ask about:

• Oral ulcers
• Genital ulcers
• Psoriatic plaques
• Erythema nodosum
• Vitiligo
• Rash
• Herpetic lesions

Important associations include:

• Behçet disease
• Psoriasis
• Reactive arthritis
• Sarcoidosis
• Syphilis
• VKH

Musculoskeletal Symptoms

Ask about:

• Inflammatory back pain
• Sacroiliac pain
• Morning stiffness
• Peripheral arthritis
• Enthesitis
• Tendon pain

These suggest:

• Ankylosing spondylitis
• Reactive arthritis
• Psoriatic arthritis
• IBD-associated arthritis

Gastrointestinal Symptoms

Ask about:

• Chronic diarrhea
• Bloody stool
• Abdominal pain

These may suggest:

• Inflammatory bowel disease
• Reactive arthritis

Genitourinary Symptoms

Ask about:

• Urethritis
• Genital ulcers
• Dysuria
• Epididymitis

These may be relevant to:

• Reactive arthritis
• Behçet disease
• Syphilis
• HSV

Renal Symptoms

Consider:

• Abnormal urinalysis
• Elevated creatinine
• Systemic symptoms

in suspected:

Tubulointerstitial nephritis and uveitis (TINU)

Neurologic Symptoms

Ask about:

• Headache
• Meningitic symptoms
• Cranial nerve palsies
• Sensory or motor symptoms

Possible associations include:

• Sarcoidosis
• Behçet disease
• Lyme disease
• Multiple sclerosis
• VKH
• Lymphoma

Physical Examination

External Examination

Assess:

• Skin
• Joints
• Oral cavity
• Lymph nodes
• Neurologic findings

Pupils

Possible findings include:

• Miosis
• Irregular pupil
• Posterior synechiae
• Seclusio pupillae

A fixed irregular pupil may indicate extensive synechiae.

Intraocular Pressure

IOP may be:

• Low from ciliary body shutdown
• Normal
• Elevated from trabeculitis, inflammation, or steroid response

Elevated IOP is particularly associated with:

• Herpetic anterior uveitis
• Fuchs uveitis syndrome
• Posner-Schlossman syndrome

Gonioscopy

Gonioscopy may reveal:

• Peripheral anterior synechiae
• Angle KPs
• Secondary angle closure
• Abnormal angle vessels

In Fuchs uveitis syndrome, abnormal angle vessels may predispose to bleeding during surgery.

Conjunctiva and Sclera

Typical finding:

Ciliary flush

Associated episcleritis or scleritis may suggest systemic inflammatory disease.

Cornea

Important findings include:

• Small punctate KPs
• Fine stellate KPs
• Corneal edema
• Reduced corneal sensation in herpetic disease
• Band keratopathy in chronic uveitis, especially JIA

Keratic Precipitates

In NGAU, KPs are usually:

• Fine
• Small
• Punctate
• Stellate

Large greasy “mutton-fat” KPs suggest granulomatous inflammation, although overlap can occur.

Iris Findings

Look for:

• Posterior synechiae
• Iris atrophy
• Transillumination defects
• Heterochromia
• Iris nodules
• Pupillary membranes

Posterior Synechiae

Posterior synechiae occur when the iris adheres to the anterior lens capsule.

Complications include:

• Irregular pupil
• Seclusio pupillae
• Iris bombe
• Secondary angle closure

Cycloplegics help reduce this risk.

Hypopyon

Hypopyon may occur in:

• HLA-B27-associated uveitis
• Behçet disease
• Severe infectious uveitis
• Masquerade syndromes

A hypopyon should prompt careful consideration of infection before escalating immunosuppression.

Hyphema

Possible causes in an inflamed eye include:

• Herpetic disease
• Fuchs uveitis syndrome
• UGH syndrome
• Juvenile xanthogranuloma
• Neovascularization
• Leukemia

Anterior Chamber Cell Grading

Using SUN criteria with a 1 × 1 mm slit beam:

• 0: <1 cell
• 0.5+: 1–5 cells
• 1+: 6–15 cells
• 2+: 16–25 cells
• 3+: 26–50 cells
• 4+: >50 cells

Anterior Chamber Flare

Typical grading:

• 0: none
• 1+: faint
• 2+: moderate
• 3+: marked
• 4+: intense, often with fibrin

Lens and Anterior Vitreous

Look for:

• Posterior subcapsular cataract
• Lenticular precipitates
• Retained lens material
• IOL-related irritation
• Cyclitic membrane
• Anterior vitreous cells

Dilated Fundus Examination

A complete dilated examination is essential to exclude posterior disease.

Look for:

• Vitritis
• CME
• Retinal vasculitis
• Toxoplasmosis scars
• Retinal necrosis
• Choroidal lesions
• Snowballs/snowbanking
• Intraocular foreign body
• Retinal or choroidal infiltrates

Diagnostic Workup

A laboratory workup should be targeted, not indiscriminate.

Workup is particularly indicated when disease is:

• Bilateral
• Recurrent
• Severe
• Chronic
• Atypical
• Poorly responsive to treatment
• Associated with systemic symptoms

Common Initial Tests

Depending on presentation, consider:

• Syphilis serology
• TB testing
• HLA-B27
• Chest imaging for sarcoidosis/TB
• Lyme testing only when epidemiologically appropriate

HLA-B27 Testing

Useful particularly in:

• Recurrent acute unilateral anterior uveitis
• Young adults
• Inflammatory back pain
• Known spondyloarthropathy

JIA Evaluation

In a child with suspected JIA-associated uveitis, consider:

• ANA
• Rheumatologic assessment

JIA uveitis may be asymptomatic, making screening crucial.

TINU Evaluation

If TINU is suspected:

• Serum creatinine
• Urinalysis
• Urine β2-microglobulin

may be useful.

Renal consultation may be appropriate.

Vasculitis / Scleritis Workup

If uveitis is associated with:

• Scleritis
• Peripheral ulcerative keratitis
• Sinopulmonary disease
• Systemic vasculitic symptoms

consider targeted testing such as:

• ANCA
• ESR
• CRP

Imaging

OCT

OCT is useful for detecting and monitoring:

• Cystoid macular edema
• Epiretinal membrane
• Macular structural damage

Fluorescein Angiography

Useful when there is concern for:

• CME
• Retinal vasculitis
• Posterior segment inflammatory disease

B-Scan Ultrasonography

Useful when media opacity prevents visualization of the posterior segment.

Anterior Chamber or Vitreous Sampling

May be considered in selected cases for:

• HSV PCR
• VZV PCR
• CMV PCR
• Toxoplasma PCR
• Cytology for lymphoma or leukemia

This is particularly useful in atypical or treatment-resistant disease.

Differential Diagnosis

Important causes include:

• HLA-B27-associated anterior uveitis
• Ankylosing spondylitis
• Psoriatic arthritis
• IBD-associated uveitis
• Reactive arthritis
• JIA
• HSV
• VZV
• CMV
• Posner-Schlossman syndrome
• Fuchs uveitis syndrome
• Behçet disease
• TINU
• Traumatic iritis
• Lens-induced uveitis
• UGH syndrome
• Drug-induced uveitis
• Intraocular lymphoma
• Idiopathic anterior uveitis

Other infectious or granulomatous diseases such as syphilis, TB, and sarcoidosis can also present with anterior inflammation and should be considered when appropriate.

Treatment

First-Line – Topical Corticosteroids

The mainstay of treatment for noninfectious anterior uveitis is:

Topical corticosteroid therapy

Common choices include:

• Prednisolone acetate 1%
• Difluprednate 0.05%

Frequency depends on severity.

Severe inflammation may initially require very frequent dosing, then gradual tapering according to clinical response.

Important Treatment Principle

Do not taper corticosteroids based only on symptoms.

Taper according to:

• Anterior chamber cell count
• Flare
• Clinical course

Tapering too quickly may cause recurrence.

Cycloplegics

Cycloplegic or mydriatic agents are used to:

• Reduce ciliary spasm
• Relieve pain
• Prevent posterior synechiae
• Break fresh synechiae

Options include:

• Homatropine
• Cyclopentolate
• Atropine in severe disease

Herpetic Anterior Uveitis

If HSV or VZV is suspected, treatment generally includes:

• Systemic antiviral therapy
• Topical corticosteroid under antiviral cover
• IOP-lowering therapy when needed

Steroid monotherapy should be avoided when active herpetic disease is suspected.

Periocular Steroids

Sub-Tenon corticosteroid injection may be considered for:

• Chronic uveitis
• Significant CME
• Poor response to topical therapy
• Poor adherence

Monitor closely for:

• Steroid-induced ocular hypertension
• Cataract

Systemic Corticosteroids

Oral prednisone may be needed when inflammation is:

• Severe
• Bilateral
• Posteriorly extensive
• Refractory to topical/local therapy

Prolonged high-dose therapy should generally be avoided when steroid-sparing therapy is appropriate.

Steroid-Sparing Immunomodulatory Therapy

Consider when:

• Disease is chronic
• Relapses occur during steroid taper
• Long-term systemic corticosteroid is required
• Steroid toxicity develops

Options include:

• Methotrexate
• Mycophenolate mofetil
• Azathioprine
• Cyclosporine
• Tacrolimus
• Biologic therapy

These are usually managed with rheumatology or a uveitis specialist.

Biologic Therapy

Biologic agents, especially TNF-alpha inhibitors, may be particularly useful in:

• JIA-associated uveitis
• Behçet disease
• Spondyloarthropathy-associated uveitis
• Refractory noninfectious uveitis

Systemic infection screening is essential before biologic therapy.

Monitoring During Immunosuppression

Depending on the medication, monitoring may include:

• CBC
• Liver function
• Renal function
• Blood pressure
• Infection screening

Monitoring intervals depend on the specific drug and specialist protocol.

Glaucoma Management

Glaucoma may result from:

• Inflammatory trabeculitis
• Peripheral anterior synechiae
• Pupillary block
• Steroid response

Treatment may require:

• IOP-lowering drops
• Glaucoma specialist referral
• Surgery if uncontrolled

Cataract

Posterior subcapsular cataract may result from:

• Chronic inflammation
• Corticosteroid exposure

Cataract surgery is usually planned when inflammation has been well controlled.

Cystoid Macular Edema

CME is a major cause of reduced vision.

Treatment may include:

• Topical steroids
• Periocular steroid
• Intravitreal steroid
• Systemic anti-inflammatory treatment
• Steroid-sparing immunomodulation

Surgery

Possible procedures include:

• Cataract extraction
• Glaucoma surgery
• Vitrectomy in selected cases

Surgery is ideally performed when inflammation is well controlled.

Referral

Consider referral to:

• Uveitis specialist for recurrent or atypical disease
• Rheumatology for HLA-B27/JIA/systemic inflammatory disease
• Gastroenterology for IBD
• Pulmonology for sarcoidosis
• Retina specialist for CME or posterior involvement
• Glaucoma specialist for uncontrolled IOP

Follow-Up

During active inflammation, follow-up may initially be:

• Weekly
• Every 1–2 weeks

depending on severity.

Once the anterior chamber reaction improves and steroid dosing decreases, visits may be spaced out.

Patient Monitoring

Monitor:

• Visual acuity
• Anterior chamber cells
• Flare
• IOP
• Posterior synechiae
• Cataract
• CME
• Response to steroid taper

Prognosis

Prognosis depends on:

• Etiology
• Severity
• Recurrence
• Chronicity
• Treatment response
• Development of complications

Many acute unilateral cases have an excellent prognosis with appropriate treatment.

Chronic or recurrent disease may lead to permanent visual impairment.

Complications

Important complications include:

• Posterior synechiae
• Seclusio pupillae
• Iris bombe
• Secondary angle closure
• Steroid-induced glaucoma
• Chronic inflammatory glaucoma
• Posterior subcapsular cataract
• Cystoid macular edema
• Band keratopathy
• Hypotony in severe chronic disease

Ophthalmology Pearls

• NGAU = pain + photophobia + ciliary flush + anterior chamber cells/flare.
• Fine or stellate KPs favor a non-granulomatous pattern.
• HLA-B27 uveitis is typically acute, unilateral, recurrent, and can be severe with hypopyon.
• Anterior uveitis with high IOP should raise suspicion for herpetic disease, Fuchs uveitis syndrome, or Posner-Schlossman syndrome.
• Cycloplegics relieve pain and help prevent posterior synechiae.
• Always perform a dilated fundus examination to exclude posterior involvement.
• Laboratory testing should be targeted to the clinical picture, not ordered indiscriminately.
• Do not suppress presumed infectious uveitis with corticosteroids alone.
• CME, cataract, and glaucoma are major causes of long-term visual loss.
• Recurrent or steroid-dependent disease should prompt consideration of systemic immunomodulatory therapy.

Ophthalmology – Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)

Basics

Description

Non-arteritic anterior ischemic optic neuropathy (NAION) is an acute ischemic optic neuropathy caused by impaired perfusion of the anterior optic nerve head.

It classically presents with:

• Sudden
• Painless
• Unilateral visual loss
• Optic disc edema
• Relative afferent pupillary defect
• Characteristic visual field loss

NAION is one of the most common acute optic neuropathies in older adults.

Epidemiology

NAION most commonly occurs after age 50.

Reported incidence is approximately:

2–10 cases per 100,000 persons older than 50 years per year

Thousands of new cases occur annually in the United States.

It can also occur in younger adults, particularly when vascular or anatomic risk factors are present.

Risk Factors

Important associated risk factors include:

• Hypertension
• Diabetes mellitus
• Hyperlipidemia
• Obstructive sleep apnea
• Nocturnal hypotension
• Systemic hypoperfusion
• Small-vessel vascular disease
• Smoking
• Migraine in some patients

Anatomic susceptibility also plays a major role.

Medication Associations

Drugs reported in association with NAION include:

• Amiodarone
• Phosphodiesterase-5 inhibitors used for erectile dysfunction

The relationship between erectile dysfunction medications and NAION remains uncertain, and a direct causal relationship has not been definitively established.

Genetics

No consistent Mendelian genetic cause of typical NAION has been established.

Familial cases are uncommon.

Pathophysiology

NAION is believed to result from transient or sustained hypoperfusion of the:

Short posterior ciliary arterial circulation supplying the optic nerve head

This produces ischemia of the retrolaminar/prelaminar optic nerve.

Subsequent:

• Axonal swelling
• Optic disc edema
• Compartment-like crowding

may worsen ischemia in an already anatomically crowded disc.

“Disc at Risk”

The classic structural predisposition is a:

Small, crowded optic nerve head with a very small or absent physiologic cup

This is commonly called the:

“Disc at risk.”

The fellow eye often demonstrates this appearance.

A crowded disc may permit initial axonal swelling to compress adjacent capillaries and worsen ischemic damage.

Systemic Hypoperfusion

NAION is often first noticed on awakening.

This has led to the hypothesis that:

• Physiologic nocturnal blood pressure reduction
• Excessive nighttime antihypertensive effect
• Obstructive sleep apnea

may reduce optic nerve perfusion in susceptible patients.

However, blood pressure management must be individualized because uncontrolled hypertension is itself harmful.

Commonly Associated Conditions

Common associations include:

• Diabetes mellitus
• Hypertension
• Hyperlipidemia
• Obstructive sleep apnea
• Atherosclerotic vascular disease
• Migraine

Diagnosis

NAION is primarily a clinical diagnosis.

The typical patient has:

Acute painless monocular visual loss + swollen optic disc + corresponding visual field defect

History

Typical features include:

• Sudden visual loss in one eye
• Usually painless
• Often noticed on awakening
• Stable or mildly progressive decline over hours to days

Patients may describe:

• Blurred vision
• Dark area in the visual field
• Loss of upper or lower half of vision
• Reduced contrast
• Color desaturation

Pain

Significant orbital pain or pain with eye movement is unusual.

Its presence should raise consideration of:

• Optic neuritis
• Orbital disease
• Other inflammatory optic neuropathies

Visual Acuity

Visual acuity is variable.

Patients may retain relatively good central acuity despite a large visual field defect, or may develop marked central visual loss if the papillomacular fibers are affected.

Pupillary Examination

A unilateral or asymmetric case usually produces:

Relative afferent pupillary defect (RAPD)

Color Vision

Color vision is commonly reduced.

Patients may demonstrate:

• Dyschromatopsia
• Red desaturation
• Reduced color discrimination

The deficit often corresponds roughly with the degree of optic nerve dysfunction.

Visual Field Defect

The classic visual field abnormality is:

Altitudinal field loss

Most often:

• Inferior altitudinal defect

but superior altitudinal loss can also occur.

Other patterns include:

• Arcuate defects
• Central defects
• Nasal steps
• Generalized depression

Optic Disc Appearance

During the acute phase, examination shows:

• Optic disc edema
• Often segmental swelling
• Hyperemic or occasionally pale disc
• Peripapillary splinter or flame hemorrhages

Disc hemorrhages are common and support the diagnosis.

Fellow Eye

The fellow optic nerve commonly shows:

• Small disc
• Minimal or absent cup
• Crowded appearance

This is the classic disc at risk.

Critical Alert – Exclude Giant Cell Arteritis

In an older patient with acute ischemic optic neuropathy, the most important immediate distinction is between:

• NAION
• Arteritic anterior ischemic optic neuropathy (AAION) from giant cell arteritis

AAION is an ophthalmic emergency because the fellow eye can become involved rapidly, causing bilateral severe visual loss.

Symptoms Suggesting Giant Cell Arteritis

Ask specifically about:

• New headache
• Scalp tenderness
• Jaw claudication
• Constitutional symptoms
• Fever
• Weight loss
• Polymyalgia rheumatica symptoms
• Transient visual loss
• Diplopia

Absence of systemic symptoms does not completely exclude GCA.

NAION vs Arteritic AION

Features more suggestive of NAION include:

• Moderately reduced vision
• Hyperemic swollen disc
• Disc hemorrhages
• Crowded fellow disc
• Typical vascular risk factors

Features more suggestive of GCA/AAION include:

• Profound visual loss
• Chalky-white or pallid disc edema
• Older age
• Systemic GCA symptoms
• Markedly elevated inflammatory markers
• Retinal or choroidal ischemia

Laboratory Evaluation

Routine laboratory testing is not necessary for every classic NAION case.

However, in patients in whom GCA is possible—especially those over 50—obtain urgently:

• ESR
• CRP
• CBC with platelet count

If clinical suspicion remains high, management for GCA should not be delayed while waiting for confirmatory testing.

Visual Field Testing

Automated or kinetic perimetry is useful for:

• Documenting the baseline defect
• Monitoring recovery
• Demonstrating altitudinal or arcuate loss

Optical Coherence Tomography

OCT can document:

Acute stage

• RNFL thickening from disc edema

Chronic stage

• RNFL thinning
• Ganglion cell loss
• Optic atrophy

OCT is useful for structural follow-up but does not itself establish the vascular cause.

Fundus Photography

Useful for documenting:

• Optic disc edema
• Peripapillary hemorrhage
• Resolution of swelling
• Subsequent optic atrophy

Fluorescein Angiography

Fluorescein angiography is not usually necessary in straightforward cases.

It may show:

• Delayed disc filling
• Disc leakage

It can be useful when the diagnosis is uncertain or another retinal/choroidal ischemic process is suspected.

Neuroimaging

MRI is not routinely required in classic NAION.

Consider MRI of the brain and orbits when:

• Age is atypical
• Disc edema persists unusually long
• Progressive visual loss continues
• Pain is prominent
• Neurologic abnormalities are present
• A compressive or inflammatory optic neuropathy is suspected

Pathology

Pathologic studies demonstrate:

• Ischemic infarction of the anterior/retrolaminar optic nerve
• Subsequent axonal loss
• Optic nerve atrophy

Differential Diagnosis

Important differential diagnoses include:

• Arteritic AION from giant cell arteritis
• Optic neuritis
• Papillitis
• Papilledema
• Papillophlebitis
• Compressive optic neuropathy
• Infiltrative optic neuropathy
• Amiodarone-associated optic neuropathy
• Diabetic papillopathy
• Central retinal vein occlusion with disc edema

Amiodarone Optic Neuropathy

Amiodarone-associated optic neuropathy may resemble NAION but more often shows:

• Bilateral involvement
• Insidious onset
• Prolonged disc edema
• More gradual visual loss

Treatment

No Proven Vision-Restoring Therapy

At present, there is no established treatment proven to reliably restore vision after acute NAION.

Management therefore focuses on:

• Excluding GCA
• Optimizing systemic risk factors
• Reducing risk to the fellow eye
• Monitoring visual recovery
• Low-vision support when needed

Blood Pressure Management

Hypertension should be appropriately controlled.

However, avoid unnecessary excessive hypotension, particularly at night, in susceptible patients.

Medication timing should be discussed with the patient’s primary physician or cardiologist rather than changed independently.

Diabetes and Lipid Control

Optimize:

• Blood glucose
• HbA1c
• Lipids
• General cardiovascular health

These measures benefit overall vascular health, although they have not been proven to reverse existing NAION.

Obstructive Sleep Apnea

Patients with symptoms or risk factors for obstructive sleep apnea should be evaluated.

Relevant symptoms include:

• Loud snoring
• Witnessed apneas
• Daytime somnolence
• Morning headaches

Treatment of sleep apnea is important for systemic health and may potentially reduce recurrent hypoxic stress.

Aspirin

Aspirin has been investigated for prevention of fellow-eye NAION.

However:

There is no convincing evidence that aspirin reliably prevents NAION in the fellow eye.

Aspirin should be prescribed based on the patient’s general cardiovascular indications rather than specifically as NAION therapy.

Corticosteroids

Systemic corticosteroids have been studied, but evidence has not established them as standard therapy for NAION.

They should not be confused with the urgent high-dose corticosteroid treatment required for arteritic AION due to giant cell arteritis.

Anticoagulation

Anticoagulation has not been proven effective for routine NAION treatment.

It should only be used when there is another established medical indication.

Hyperbaric Oxygen

Hyperbaric oxygen has not demonstrated sufficient benefit to become standard treatment.

Optic Nerve Sheath Decompression

Optic nerve sheath decompression should not be performed for NAION.

Clinical trial evidence demonstrated:

• No visual benefit
• Potential worsening of visual outcomes

This procedure is considered potentially harmful in NAION.

Referral

Patients should be evaluated by an ophthalmologist, preferably:

• Neuro-ophthalmologist

when available.

Medical evaluation should address:

• Hypertension
• Diabetes
• Hyperlipidemia
• Sleep apnea
• Other vascular risk factors

Follow-Up

Typical follow-up may include:

• Early reassessment within 1–2 weeks
• Approximately 1 month
• Approximately 2–3 months

depending on clinical findings.

Course of Disc Edema

Optic disc edema usually resolves over approximately:

6–11 weeks

The disc subsequently develops:

• Segmental pallor
• Diffuse optic atrophy

Persistent swelling well beyond the expected period should prompt reconsideration of the diagnosis.

Patient Monitoring

Follow:

• Visual acuity
• Color vision
• Visual field
• Optic disc appearance
• OCT RNFL and ganglion cell measurements when useful

24-Hour Blood Pressure Monitoring

Ambulatory blood pressure monitoring is not routinely required.

It may be useful in selected patients when there is concern for:

• Excessive nocturnal hypotension
• Medication-related hypotension
• Marked blood pressure variability

Patient Education

Patients should understand that:

• The vision loss is caused by ischemic injury to the optic nerve.
• Recovery is variable.
• The damaged field may remain permanently reduced.
• The fellow eye is also at risk.

They should seek prompt assessment for new visual symptoms in the other eye.

Medication Counseling

Patients should discuss potentially relevant medications with their physicians, particularly:

• Antihypertensives taken at night
• Amiodarone
• PDE-5 inhibitors

Medications should not be stopped without medical supervision.

Prognosis

Visual loss generally becomes stable after the acute phase.

Many patients have persistent visual field defects.

A meaningful spontaneous improvement in visual acuity can occur in a subset of patients over several months.

Fellow-Eye Risk

The fellow eye has a significant but not inevitable risk of developing NAION.

A commonly cited risk is approximately:

15% over 5 years

Risk may be higher in patients with persistent systemic and anatomic risk factors.

Recurrence

Recurrence in the same eye is relatively uncommon because optic atrophy and tissue loss may reduce the crowding that contributed to the original event.

Complications

Potential consequences include:

• Permanent visual field defect
• Persistent reduction in visual acuity
• Dyschromatopsia
• Optic atrophy
• Bilateral visual impairment if the fellow eye later becomes involved

Ophthalmology Pearls

• NAION = sudden painless monocular visual loss + swollen optic disc + altitudinal visual field defect.
• Symptoms are frequently first noticed on awakening.
• The fellow eye often has a small cup-to-disc ratio—the classic “disc at risk.”
• Peripapillary splinter hemorrhages commonly accompany acute disc edema.
• In every older patient with acute ischemic optic neuropathy, exclude giant cell arteritis urgently.
• A pale, chalky swollen optic disc with profound visual loss should raise strong concern for arteritic AION.
• There is currently no proven vision-restoring treatment for NAION.
• Optimize modifiable risks, particularly diabetes, hypertension, hyperlipidemia, and obstructive sleep apnea.
• Avoid unnecessary systemic hypotension, especially excessive nocturnal hypotension.
• Aspirin, anticoagulation, steroids, and hyperbaric oxygen have not been proven to prevent or reverse typical NAION.
• Optic nerve sheath decompression is ineffective and potentially harmful.
• Disc edema usually resolves within several weeks and is followed by optic atrophy.
• Fellow-eye involvement occurs in roughly 15% over 5 years, making long-term risk-factor management important.

Ophthalmology – Neuroretinitis

Basics

Description

Neuroretinitis is an inflammatory optic neuropathy characterized by:

• Optic disc edema
• Subsequent development of macular hard exudates in a stellate or “macular star” pattern
• Variable visual loss

It is usually:

• Unilateral
• Painless
• Self-limited in immunocompetent patients

Bilateral disease can occur but is less common.

Historically called Leber idiopathic stellate neuroretinitis, many cases are now known to have an infectious or immune-mediated cause.

The most important infectious association is:

Bartonella henselae – cat-scratch disease

Epidemiology

Neuroretinitis:

• Can occur at any age
• Has no strong sex predilection
• Affects either eye with similar frequency

The true prevalence is uncertain.

Cat exposure is common among patients with Bartonella-associated neuroretinitis.

Risk Factors

Important historical risk factors include:

• Recent contact with cats, especially kittens
• Cat scratch or bite
• Flea exposure
• Recent febrile or flu-like illness
• Immunocompromised state
• Exposure to tuberculosis
• Tick exposure in Lyme-endemic areas
• Sexual risk factors relevant to syphilis or HIV
• Exposure to animals associated with zoonotic infections

A viral-like illness may precede otherwise idiopathic neuroretinitis.

Pathophysiology

The characteristic process begins with inflammation and leakage from the:

Optic nerve head

This causes:

• Optic disc edema
• Peripapillary retinal edema
• Leakage of lipid-rich fluid into the outer plexiform layer of the macula

As the fluid resolves, lipid deposits remain in a radial configuration around the fovea, producing the:

Macular star

Macular Star Formation

The macular star is often not present at the initial examination.

It typically develops days to several weeks after the onset of optic disc edema and visual symptoms.

Therefore:

Early neuroretinitis may resemble isolated optic neuritis or other causes of disc edema.

Etiology

Neuroretinitis may be:

• Infectious
• Postinfectious
• Immune-mediated
• Idiopathic

Infectious Causes

Important infectious causes include:

• Bartonella henselae
• Syphilis
• Tuberculosis
• Lyme disease
• Toxoplasmosis
• Toxocariasis
• Leptospirosis
• Brucellosis
• HIV-associated infections
• Viral infections

Other infectious etiologies should be considered according to:

• Geography
• Exposure history
• Immune status

Bartonella henselae

Bartonella henselae is the classic and most common identifiable cause of neuroretinitis in many regions.

It causes cat-scratch disease.

Transmission commonly involves:

• Cats, especially kittens
• Cat scratches
• Cat bites
• Fleas

A scratch is not always recalled.

Cat-Scratch Disease

Systemic manifestations may include:

• Fever
• Malaise
• Headache
• Regional lymphadenopathy

Ocular manifestations can include:

• Neuroretinitis
• Parinaud oculoglandular syndrome
• Retinitis
• Choroiditis
• Retinal vascular occlusion

Diagnosis

Diagnosis is based on the characteristic combination of:

Optic disc edema + delayed macular star formation

together with clinical and laboratory evaluation for an underlying cause.

History

Patients commonly report:

• Blurred vision
• Decreased central vision
• Central or paracentral scotoma
• Reduced color vision
• Metamorphopsia

Vision may range from near normal to profound impairment.

Pain

Unlike typical demyelinating optic neuritis:

Neuroretinitis is usually painless.

Pain with eye movement is less characteristic.

Systemic Symptoms

Ask about:

• Fever
• Malaise
• Recent viral-like illness
• Lymph node enlargement
• Cat exposure
• Cat scratches or bites
• Tick exposure
• Tuberculosis exposure
• Sexual history
• Rash
• Arthralgia
• Immunosuppression

Physical Examination

Visual Acuity

Visual acuity may range widely depending on:

• Severity of optic nerve involvement
• Macular edema
• Associated retinitis

Pupillary Examination

A unilateral or asymmetric case usually produces a:

Relative afferent pupillary defect

Color Vision

Acquired dyschromatopsia is common.

Patients may have:

• Reduced color saturation
• Red desaturation
• Generalized color discrimination loss

Optic Disc

Typical initial finding:

Optic disc edema

This may be:

• Diffuse
• Hyperemic
• Associated with peripapillary retinal edema
• Accompanied by small hemorrhages in some cases

Macular Star

The hallmark finding is:

Radially arranged hard exudates around the fovea

forming a star-shaped pattern.

These deposits may appear after the onset of disc edema, so repeat examination can establish the diagnosis.

Chorioretinal Lesions

Small focal chorioretinal lesions may occur, especially with infectious etiologies such as Bartonella.

Visual Field Defects

Possible defects include:

• Cecocentral scotoma
• Central scotoma
• Arcuate defect
• Altitudinal defect

The most typical pattern is central or cecocentral involvement.

Bilateral Disc Edema

Bilateral neuroretinitis is possible.

However, bilateral optic disc swelling should also raise concern for:

• Papilledema from raised intracranial pressure
• Hypertensive emergency
• Infiltrative disease
• Infectious optic neuropathy

Appropriate neuroimaging and, when indicated, lumbar puncture may be required.

Diagnostic Testing

Testing should be guided by history, examination, geography, and immune status rather than automatically ordering every possible serology.

Bartonella Serology

When cat-scratch disease is suspected, obtain:

• Bartonella henselae IgG
• Bartonella henselae IgM

A significantly elevated or rising IgG titer and/or compatible IgM supports recent infection.

Serology must be interpreted in clinical context.

Additional Laboratory Tests

Depending on the presentation, evaluation may include:

• CBC
• ESR
• CRP
• Syphilis serology
• HIV testing
• Tuberculosis testing
• Lyme serology when epidemiologically appropriate
• Toxoplasma serology
• Toxocara testing
• Sarcoidosis evaluation
• Leptospira testing
• Brucella testing

Autoimmune studies should be guided by systemic findings.

Syphilis

Syphilis is an important mimic because it can cause virtually any pattern of ocular inflammation.

Testing generally includes:

• Treponemal test
• Nontreponemal test

Ocular syphilis requires systemic treatment.

Tuberculosis

Consider tuberculosis when there is:

• Relevant exposure
• Endemic residence
• Systemic symptoms
• Suggestive ocular inflammation

Testing may include:

• Interferon-gamma release assay
• Tuberculin skin testing
• Chest imaging when appropriate

MRI

MRI of the brain and orbits with contrast may be performed when:

• The diagnosis is uncertain
• Visual loss is severe
• Neurologic symptoms are present
• Bilateral disc edema is present
• A compressive or demyelinating lesion must be excluded

MRI can demonstrate optic nerve or optic disc enhancement but may also be normal.

Optical Coherence Tomography

OCT is very useful for documenting:

• Optic disc edema
• Peripapillary RNFL thickening
• Macular edema
• Subretinal fluid
• Hard exudates
• Later optic nerve thinning

Serial OCT is useful for monitoring recovery.

Fluorescein Angiography

FA typically demonstrates:

• Leakage from optic disc vessels
• Progressive optic disc hyperfluorescence
• Late disc staining

It may also identify:

• Retinal vascular inflammation
• Focal chorioretinal lesions
• Macular leakage

Fundus Photography

Useful for documenting:

• Disc edema
• Macular star development
• Chorioretinal lesions
• Resolution over time

Visual Field Testing

Formal visual fields are useful for:

• Documenting central or cecocentral scotomas
• Monitoring recovery
• Identifying persistent deficits

Differential Diagnosis

Important differential diagnoses include:

• Bartonella neuroretinitis
• Demyelinating optic neuritis
• Anterior ischemic optic neuropathy
• Papilledema
• Hypertensive retinopathy
• Syphilis
• Tuberculosis
• Lyme disease
• Toxoplasmosis
• Toxocariasis
• Sarcoidosis
• Lupus
• HIV-related disease
• Leber hereditary optic neuropathy
• Infiltrative optic neuropathy
• Leukemia or lymphoma

Hypertensive Retinopathy

Severe hypertension can produce:

• Bilateral optic disc edema
• Cotton-wool spots
• Retinal hemorrhages
• Macular star

Therefore, blood pressure should always be checked in a patient presenting with a macular star.

Neuroretinitis vs Typical Optic Neuritis

Neuroretinitis

Usually:

• Painless
• Marked disc edema
• Macular star develops
• Often infectious or postinfectious
• Lower association with multiple sclerosis

Typical Demyelinating Optic Neuritis

Usually:

• Pain with eye movement
• Retrobulbar or mild disc edema
• No macular star
• Stronger association with demyelinating disease

Treatment

Treatment depends on the underlying cause.

Many idiopathic or uncomplicated Bartonella-associated cases in immunocompetent patients are:

Self-limited

and recover spontaneously.

Bartonella-Associated Neuroretinitis

The benefit of antibiotics in otherwise healthy patients with mild disease remains somewhat uncertain because spontaneous recovery is common.

Treatment is more strongly considered when there is:

• Severe visual loss
• Bilateral disease
• Significant macular involvement
• Systemic Bartonella disease
• Immunocompromise
• Persistent or progressive disease

Antibiotic Therapy

Antibiotics used for Bartonella infection may include:

• Doxycycline
• Rifampin
• Azithromycin
• Trimethoprim-sulfamethoxazole
• Other agents depending on age and systemic circumstances

For severe Bartonella neuroretinitis in adults, a commonly used specialist regimen is:

Doxycycline with rifampin

for several weeks.

Treatment should be individualized according to:

• Age
• Pregnancy status
• Immune status
• Systemic disease
• Infectious disease guidance

Immunocompromised Patients

Patients who are immunocompromised generally require treatment because they have:

• Greater risk of disseminated infection
• More prolonged disease
• More severe ocular involvement

Corticosteroids

Systemic corticosteroids may occasionally be considered as adjunctive therapy in severe inflammatory neuroretinitis.

However:

Corticosteroids should not be given alone when an untreated infectious cause remains possible.

When used for infectious neuroretinitis, they should generally be combined with appropriate antimicrobial therapy under specialist supervision.

Cause-Specific Treatment

If another infectious cause is identified, treat appropriately.

Examples include:

• Syphilis → systemic penicillin therapy
• Tuberculosis → multidrug antituberculous therapy
• Toxoplasmosis → appropriate antiparasitic therapy when indicated
• Lyme disease → guideline-directed antibiotic therapy

Referral

Patients should be evaluated by an:

• Ophthalmologist

Referral to a:

• Neuro-ophthalmologist
• Retina/uveitis specialist

is appropriate when:

• Diagnosis is uncertain
• Visual loss is severe
• Disease is bilateral
• Retinal lesions are prominent
• Recovery is atypical

Infectious disease consultation may be useful for complex infections.

Hospitalization

Most uncomplicated neuroretinitis can be treated as an outpatient.

Admission may be required for:

• Severe systemic infection
• Immunocompromised patients with disseminated disease
• Neurologic involvement
• Need for intravenous therapy
• Diagnostic uncertainty involving potentially life-threatening disease

Follow-Up

During the acute phase, follow-up should monitor:

• Visual acuity
• Pupillary response
• Color vision
• Visual field
• Optic disc edema
• Macular edema
• Macular exudates

Initial follow-up may occur every few weeks depending on severity.

Natural Course

Optic disc swelling generally resolves first.

Macular exudates may persist considerably longer.

They often resolve over:

Several months

and occasionally remain visible for many months.

Patient Education

Patients should understand that:

• Most cases have a favorable prognosis.
• Macular exudates resolve slowly.
• Vision may improve before the fundus appears completely normal.
• New neurologic or systemic symptoms require prompt evaluation.

Cat-Exposure Education

When Bartonella infection is suspected or confirmed:

• Avoid rough play with kittens.
• Wash scratches promptly.
• Avoid allowing cats to lick open wounds.
• Maintain appropriate flea control.

Cat ownership itself usually does not need to be eliminated.

Prognosis

The overall visual prognosis is usually good, especially in immunocompetent patients.

Many patients recover substantial central visual acuity over weeks to months.

Recovery may continue even while the macular star remains visible.

Poor Prognostic Factors

Residual impairment is more likely with:

• Severe initial optic nerve dysfunction
• Extensive macular involvement
• Recurrent disease
• Severe infectious disease
• Optic atrophy

Complications

Potential complications include:

• Persistent reduced visual acuity
• Central or cecocentral visual field defect
• Optic atrophy
• Dyschromatopsia
• Metamorphopsia
• Persistent macular abnormalities
• Rare permanent severe visual loss

Ophthalmology Pearls

• Neuroretinitis = optic disc edema followed by a macular star.
• The macular star may be absent initially and appear later, so early cases can be misdiagnosed.
• Bartonella henselae is the classic infectious association.
• Ask specifically about cat or kitten exposure, even if no scratch is remembered.
• Neuroretinitis is generally painless, unlike typical demyelinating optic neuritis.
• A central or cecocentral scotoma is common.
• Bilateral disc edema requires consideration of raised intracranial pressure and malignant hypertension, not just bilateral neuroretinitis.
• Always check blood pressure when a macular star is present.
• Bartonella neuroretinitis is often self-limited in immunocompetent patients, but severe or systemic disease may warrant antimicrobial treatment.
• Steroids should not be used alone when infectious neuroretinitis has not been excluded or treated.
• Visual prognosis is usually good, while the macular exudates may take months to disappear completely.

Ophthalmology – Neuroprotection in Glaucoma

Basics

Description

Neuroprotection in glaucoma refers to therapeutic strategies aimed at preserving retinal ganglion cells (RGCs), their axons, and optic nerve function independently of—or in addition to—lowering intraocular pressure (IOP).

Potential goals include:

• Preventing RGC injury
• Slowing RGC apoptosis
• Preserving optic nerve axons
• Maintaining visual field function
• Enhancing neuronal resistance to metabolic or ischemic stress
• Potentially promoting neuronal recovery or regeneration

At present, however:

IOP reduction remains the only clinically proven treatment strategy that consistently reduces the risk of glaucomatous progression.

No treatment has yet been definitively established as an independent neuroprotective therapy for glaucoma in routine clinical practice.

Why Neuroprotection Is Important

Glaucoma is a progressive optic neuropathy characterized by:

• Loss of retinal ganglion cells
• Loss of retinal nerve fiber layer
• Optic nerve head remodeling
• Progressive visual field loss

Although IOP is the most important modifiable risk factor, it does not completely explain glaucomatous damage.

Important observations include:

• Some patients with elevated IOP never develop glaucoma.
• Patients with normal-tension glaucoma develop glaucomatous optic neuropathy despite IOP measurements within the statistically normal range.
• Some patients continue to progress despite substantial IOP reduction.

Therefore, mechanisms independent of IOP probably contribute to retinal ganglion cell injury.

Pathophysiology

RGC death in glaucoma is multifactorial.

Mechanisms can broadly be divided into:

• IOP-dependent injury
• IOP-independent neuronal injury

These mechanisms interact rather than functioning as completely separate pathways.

IOP-Dependent Retinal Ganglion Cell Loss

Mechanical Theory

Elevated IOP can cause deformation of the:

Lamina cribrosa

This may produce:

• Posterior laminar bowing
• Compression of retinal ganglion cell axons
• Disturbance of axoplasmic transport
• Mechanical injury to optic nerve fibers
• Remodeling of connective tissue

Interruption of axonal transport may deprive RGCs of important neurotrophic factors.

Vascular Theory

Optic nerve damage may also be related to reduced perfusion.

A simplified concept is:

Ocular perfusion pressure ≈ arterial blood pressure − intraocular pressure

Reduced perfusion can result from:

• Increased IOP
• Low systemic blood pressure
• Nocturnal hypotension
• Vascular dysregulation
• Impaired autoregulation

This may be particularly relevant in some patients with normal-tension glaucoma.

Non-IOP-Dependent Mechanisms

Multiple cellular pathways have been implicated in glaucomatous neurodegeneration.

Important mechanisms include:

• Excitotoxicity
• Mitochondrial dysfunction
• Oxidative stress
• Neuroinflammation
• Loss of neurotrophic support
• Nitric oxide dysregulation
• Axonal transport failure
• Glial activation
• Apoptosis

Excitotoxicity

Glutamate is the major excitatory neurotransmitter of the central nervous system.

Excessive stimulation of glutamate receptors, particularly:

NMDA receptors

can result in excessive entry of:

• Calcium
• Sodium

into neurons.

Excess intracellular calcium may activate:

• Proteases
• Lipases
• Endonucleases
• Mitochondrial injury pathways

ultimately promoting apoptosis.

Although excitotoxicity is biologically plausible, targeting this pathway has not yet produced an established clinical neuroprotective treatment for glaucoma.

Retinal Ganglion Cell Apoptosis

A major final pathway of glaucomatous neuronal injury is:

Apoptosis

This is programmed cell death characterized by controlled intracellular signaling rather than acute necrosis.

Potential triggers include:

• Mechanical stress
• Ischemia
• Oxidative injury
• Mitochondrial dysfunction
• Neurotrophin deprivation
• Inflammatory mediators

Mitochondrial Dysfunction

Retinal ganglion cells have high energy requirements.

Mitochondrial dysfunction may lead to:

• Reduced ATP production
• Increased reactive oxygen species
• Abnormal calcium handling
• Greater susceptibility to metabolic stress
• Activation of apoptotic pathways

Mitochondrial vulnerability has therefore become an important area of glaucoma neuroprotection research.

Oxidative Stress

Oxidative stress occurs when production of:

Reactive oxygen species (ROS)

exceeds the antioxidant capacity of ocular tissues.

Consequences may include:

• Lipid peroxidation
• DNA damage
• Protein oxidation
• Mitochondrial dysfunction
• Trabecular meshwork injury
• RGC apoptosis

Neuroinflammation

Glaucoma is increasingly recognized as involving chronic neuroinflammatory signaling.

Potential components include:

• Activated microglia
• Astrocytes
• Complement activation
• Cytokines
• Tumor necrosis factor-alpha
• Other inflammatory mediators

Inflammation may initially be protective but become detrimental when chronically activated.

Complement System

Several complement components are upregulated in experimental glaucoma.

The complement system may participate in:

• Synaptic remodeling
• Clearance of damaged tissue
• Neuroinflammatory injury

Its exact role in human glaucoma remains under investigation.

Heat Shock Proteins

Heat shock proteins (HSPs) normally act as:

• Molecular chaperones
• Cellular stress-response proteins
• Anti-apoptotic mediators

Abnormal immune responses against heat shock proteins have been described in glaucoma.

Their role in disease progression remains incompletely defined.

Tumor Necrosis Factor-Alpha

TNF-α can be increased during optic nerve injury.

Potential effects include:

• Activation of inflammatory pathways
• Glial activation
• Mitochondrial dysfunction
• Promotion of RGC apoptosis

Nitric Oxide

Nitric oxide has normal physiologic roles in:

• Vascular regulation
• Neural signaling

Excessive nitric oxide production under pathologic conditions may contribute to:

• Oxidative/nitrosative stress
• Mitochondrial injury
• RGC loss

Loss of Neurotrophic Support

Healthy retinal ganglion cells depend on neurotrophic factors transported between the retina and brain.

Potential protective factors include:

• Brain-derived neurotrophic factor (BDNF)
• Nerve growth factor
• Ciliary neurotrophic factor

Glaucoma-associated axonal transport disruption may reduce delivery of these survival signals.

Diagnosis and Assessment of Neurodegeneration

There is currently no single clinical test that directly measures neuroprotection.

The effectiveness of a neuroprotective therapy would ideally be demonstrated by slower loss of:

• RGC structure
• Optic nerve axons
• Visual function

Visual Field Testing

Standard automated perimetry remains essential for determining functional progression.

Limitations include:

• Test-retest variability
• Learning effects
• Fatigue
• Slow rate of glaucomatous progression

As a result, proving a neuroprotective benefit may require large numbers of patients and long-term follow-up.

Optical Coherence Tomography

OCT provides objective structural measurements of:

• Peripapillary retinal nerve fiber layer
• Macular ganglion cell complex
• Ganglion cell–inner plexiform layer
• Optic nerve head parameters

Serial OCT can detect progressive structural loss, sometimes before clear visual field deterioration.

Optic Disc Photography

Serial optic nerve photography may document:

• Neuroretinal rim thinning
• Progressive cupping
• Disc hemorrhage
• Localized RNFL defects

It remains useful for longitudinal assessment.

Other Structural Technologies

Historically used technologies include:

• Scanning laser polarimetry
• Confocal scanning laser ophthalmoscopy

OCT has largely become the dominant structural imaging modality in routine glaucoma practice.

Detection of Apoptosing Retinal Cells

DARC – Detection of Apoptosing Retinal Cells

is an investigational imaging technique designed to visualize apoptotic retinal cells in vivo.

Its potential applications include:

• Earlier detection of active neurodegeneration
• Rapid assessment of treatment effects

It remains investigational and is not part of routine glaucoma management.

Requirements for a True Neuroprotective Therapy

An ideal neuroprotective agent should:

• Reach the retina and optic nerve at therapeutic concentrations
• Act on biologically relevant targets
• Improve neuronal survival
• Preserve retinal ganglion cell structure
• Preserve visual function
• Provide benefit independent of IOP lowering
• Demonstrate safety and efficacy in appropriately controlled human trials

The last requirement is particularly important.

A drug showing neuroprotection in animals is not automatically neuroprotective in humans.

Current Clinical Reality

Many compounds have shown promising neuroprotective effects in:

• Cell culture
• Retinal injury models
• Experimental glaucoma
• Animal studies

However, translation to human glaucoma has been difficult.

At present:

No pharmacologic therapy is established as a proven IOP-independent neuroprotective treatment for glaucoma.

Memantine

Memantine is an NMDA receptor antagonist originally developed for neurologic disease.

The rationale was to reduce glutamate-mediated excitotoxicity.

Experimental models suggested RGC protection.

However, large phase III glaucoma trials did not demonstrate sufficient clinical neuroprotective benefit to establish memantine as a glaucoma treatment.

Therefore:

Memantine is not recommended for routine glaucoma neuroprotection.

Brimonidine

Brimonidine is an α2-adrenergic agonist routinely used to lower IOP.

Experimental neuroprotective mechanisms include:

• Increased expression of neurotrophic factors
• Reduced excitotoxic injury
• Anti-apoptotic signaling

Some clinical observations, particularly in normal-tension glaucoma, have suggested possible benefit beyond IOP lowering.

However, limitations such as:

• High dropout rates
• Medication intolerance
• Difficulty separating IOP effects from true neuroprotection

mean that independent neuroprotection has not been conclusively proven.

Brimonidine should therefore be used primarily as an:

IOP-lowering medication

rather than prescribed specifically as a proven neuroprotectant.

Betaxolol

Betaxolol is a relatively β1-selective topical beta-blocker.

Experimental mechanisms proposed include:

• Reduced calcium influx
• Protection against excitotoxicity
• Improved retinal or optic nerve perfusion

Definitive independent neuroprotective benefit in humans has not been established.

Its proven role remains:

IOP reduction

Calcium Channel Blockers

Calcium channel blockers have been investigated because they may:

• Reduce intracellular calcium overload
• Reduce vasospasm
• Improve ocular blood flow

This concept may be of interest in some patients with vascular dysregulation or normal-tension glaucoma.

However:

There is insufficient evidence to recommend systemic calcium channel blockers specifically for glaucoma neuroprotection.

Systemic hypotension from these drugs could theoretically worsen optic nerve perfusion in susceptible patients.

Ginkgo Biloba

Ginkgo biloba extract has proposed:

• Antioxidant
• Vasoregulatory
• Mitochondrial

effects.

Small studies have explored its use, particularly in normal-tension glaucoma.

However:

• Evidence remains limited
• Preparations vary
• Drug interactions and bleeding risk must be considered

It is not an established glaucoma treatment.

Vitamin E

Vitamin E acts as an antioxidant and scavenger of lipid peroxyl radicals.

Although antioxidant therapy has theoretical appeal:

Vitamin E has not been proven to prevent glaucomatous RGC loss in clinical practice.

High-dose supplementation should not be recommended solely for glaucoma without another indication.

Neurotrophins

Potential neurotrophic therapies include:

• BDNF
• Nerve growth factor
• Ciliary neurotrophic factor

These can enhance neuronal survival experimentally.

Challenges include:

• Delivering adequate concentrations to RGCs
• Short duration of effect
• Receptor downregulation
• Potential activation of unwanted signaling pathways

They remain investigational.

Coenzyme Q10

Coenzyme Q10 is important in:

• Mitochondrial electron transport
• ATP production
• Antioxidant defense

Experimental studies have suggested possible protection against mitochondrial and oxidative injury.

However, definitive human evidence for glaucoma neuroprotection is lacking.

Nicotinamide

Nicotinamide (vitamin B3) has become an important area of modern glaucoma research because it supports:

• NAD metabolism
• Mitochondrial function
• Cellular energy homeostasis

Experimental glaucoma models have shown substantial RGC protection, and early human studies have investigated potential functional effects.

However:

Nicotinamide remains investigational for glaucoma neuroprotection and is not yet established as standard treatment.

High doses can also produce systemic toxicity and should not be self-prescribed for glaucoma.

Citicoline

Citicoline has been studied for possible:

• Neuroprotective
• Neuroenhancing
• Membrane-stabilizing

effects.

Small clinical studies have suggested possible improvement in electrophysiologic or functional parameters.

However:

• Evidence is not sufficient to establish long-term prevention of glaucoma progression.
• It is not a replacement for IOP-lowering therapy.

Glatiramer Acetate

Glatiramer acetate, used in multiple sclerosis, has shown neuroprotective effects in some experimental optic nerve injury models.

Its proposed mechanism involves:

• Immunomodulation
• Protective autoimmunity

It is not an established treatment for glaucoma.

Heat Shock Protein Modulation

Compounds that enhance protective heat shock protein pathways have shown experimental benefit.

For example, geranylgeranylacetone has been investigated for its ability to increase HSP expression.

This approach remains experimental.

Nitric Oxide Synthase Inhibitors

Nitric oxide pathway modulation has demonstrated potential neuroprotection in experimental models.

However:

• Nitric oxide has both protective and harmful physiologic roles.
• Systemic or ocular manipulation is complex.

No nitric oxide synthase inhibitor is established for glaucoma neuroprotection.

Photobiomodulation

Red or near-infrared light therapy has been investigated for potential:

• Mitochondrial stimulation
• Anti-inflammatory effects
• Antioxidant effects
• Anti-apoptotic effects

This remains an experimental strategy rather than standard glaucoma treatment.

Neuroregeneration

Neuroprotection aims to preserve surviving RGCs.

A more ambitious goal is:

Neuroregeneration

which would require:

• Regrowth of damaged axons
• Restoration of connections with central visual targets
• Functional reconstruction of the optic nerve pathway

This remains an active research field and is not currently achievable in routine clinical glaucoma care.

IOP Reduction as Indirect Neuroprotection

Although conventional glaucoma medications are not usually classified as neuroprotectants, reducing IOP protects RGCs by reducing the primary mechanical and physiologic stress on the optic nerve.

Established treatments include:

• Prostaglandin analogs
• Beta-blockers
• Alpha agonists
• Carbonic anhydrase inhibitors
• Rho kinase inhibitors
• Laser trabeculoplasty
• Incisional glaucoma surgery
• Minimally invasive glaucoma procedures in selected patients

From a practical standpoint:

Effective IOP lowering remains the most important proven form of RGC preservation.

Systemic Factors Relevant to RGC Protection

Neuroprotection may also involve optimizing systemic contributors to optic nerve stress.

Important considerations include:

• Avoiding severe nocturnal hypotension
• Treating significant sleep apnea
• Controlling diabetes
• Controlling vascular risk factors
• Avoiding smoking
• Maintaining general cardiovascular health

These measures may be particularly relevant in patients with normal-tension glaucoma, although they do not substitute for IOP control.

Follow-Up

Patients with glaucoma should be monitored longitudinally with:

• IOP measurement
• Gonioscopy when appropriate
• Optic disc examination
• OCT RNFL
• Macular ganglion cell analysis
• Standard automated perimetry

Progression should be assessed using both:

Structural + functional information

When Glaucoma Progresses Despite “Normal” IOP

If progression continues despite apparently controlled pressure:

• Confirm true progression.
• Review medication adherence.
• Look for IOP fluctuations or peaks.
• Reassess target IOP.
• Consider lowering the target further.
• Evaluate corneal thickness and other measurement issues.
• Review systemic hypotension.
• Consider sleep apnea or vascular dysregulation.
• Exclude nonglaucomatous optic neuropathy when findings are atypical.

The response should generally be to optimize proven glaucoma management rather than substitute an unproven neuroprotective supplement.

Clinical Challenges in Neuroprotection Research

Demonstrating neuroprotection is difficult because:

• Glaucoma progresses slowly.
• Visual fields are variable.
• Structural and functional changes may not occur simultaneously.
• IOP itself affects progression and confounds study results.
• Very long trials may be required.
• RGC death occurs at different rates among patients.

A true clinical trial must separate:

IOP-lowering benefit from independent neuronal protection.

Prognosis

The concept of neuroprotection is scientifically compelling and remains a major area of glaucoma research.

However, current evidence supports:

Aggressive control of IOP as the cornerstone of preventing glaucomatous visual loss.

Future therapies may combine:

• IOP lowering
• Neuroprotection
• Mitochondrial support
• Neuroinflammation modulation
• Axonal regeneration

Ophthalmology Pearls

• Glaucoma is a retinal ganglion cell neurodegenerative disease, not simply a disease of high IOP.
• IOP remains the only major modifiable risk factor with unequivocal clinical evidence for reducing glaucoma progression.
• Proposed non-IOP mechanisms include excitotoxicity, mitochondrial dysfunction, oxidative stress, neuroinflammation, impaired axonal transport, and loss of neurotrophic support.
• Memantine showed promise experimentally but failed to establish meaningful neuroprotection in phase III glaucoma trials.
• Brimonidine has experimental neuroprotective properties, but independent clinical neuroprotection remains unproven.
• Betaxolol, Ginkgo biloba, vitamin E, CoQ10, citicoline, neurotrophins, and other agents remain unproven or investigational for direct glaucoma neuroprotection.
• Nicotinamide is a promising modern research target, particularly through mitochondrial and NAD-related mechanisms, but is not established standard therapy.
• OCT and visual field testing remain the main methods for monitoring glaucomatous structural and functional progression.
• Progression despite apparently controlled IOP usually warrants a lower target IOP and reassessment of other risk factors, not replacement of proven therapy with an experimental neuroprotectant.
• At present, the most reliable way to protect retinal ganglion cells clinically is still effective and sustained reduction of intraocular pressure.

Ophthalmology – Neurofibromatosis

Basics

Description

Neurofibromatosis refers to inherited tumor-predisposition syndromes affecting the:

• Nervous system
• Skin
• Eyes
• Bones
• Soft tissues

The two historically recognized major forms are:

• Neurofibromatosis type 1 (NF1) – formerly von Recklinghausen disease
• NF2-related schwannomatosis – historically called neurofibromatosis type 2 or central neurofibromatosis

NF1 and NF2 are genetically and clinically distinct disorders.

Neurofibromatosis Type 1

NF1 is the much more common form.

Important ophthalmic manifestations include:

• Lisch nodules
• Optic pathway glioma
• Choroidal abnormalities
• Plexiform neurofibroma involving the eyelid/orbit
• Proptosis
• Strabismus
• Sphenoid wing dysplasia

NF2-Related Schwannomatosis

NF2-related schwannomatosis is characterized predominantly by tumors of the central and peripheral nervous systems.

The hallmark is:

Bilateral vestibular schwannomas

Important ocular manifestations include:

• Early-onset cataract
• Epiretinal membrane
• Retinal hamartoma
• Optic nerve sheath meningioma
• Strabismus or cranial nerve palsies from intracranial tumors

Epidemiology

NF1

Occurs in approximately:

1 in 3,000–3,500 individuals

NF2-Related Schwannomatosis

Much rarer, traditionally estimated at approximately:

1 in 25,000–60,000

Both sexes are affected approximately equally.

Genetics

Both NF1 and NF2-related schwannomatosis are inherited in an:

Autosomal dominant pattern

However, many patients have a new pathogenic variant without an affected parent.

NF1 Gene

The NF1 gene is located on:

Chromosome 17q11.2

It encodes:

Neurofibromin

Neurofibromin acts as a tumor suppressor and negatively regulates RAS signaling.

NF2 Gene

The NF2 gene is located on:

Chromosome 22q12

It encodes:

Merlin, also called schwannomin.

Merlin functions as a tumor-suppressor protein involved in cellular growth regulation.

Penetrance and Expression

NF1 has:

• Very high penetrance
• Markedly variable expression

Thus, members of the same family may have very different disease severity.

Mosaic forms can also occur.

Genetic Counseling

Because inheritance is autosomal dominant, an affected individual generally has a:

50% chance of transmitting the pathogenic variant to each child.

Genetic counseling is appropriate for:

• Affected patients
• Parents
• Families planning pregnancy

Prenatal and preimplantation genetic testing may be possible when the familial pathogenic variant is known.

Pathophysiology

Both neurofibromin and merlin act as tumor suppressors.

Loss of normal tumor-suppressor function predisposes to development of:

• Schwannomas
• Neurofibromas
• Gliomas
• Meningiomas
• Other benign and malignant tumors

Neurofibromatosis Type 1 – Diagnostic Features

Modern diagnostic criteria for NF1 incorporate clinical findings and molecular testing.

In a patient without an affected parent, the diagnosis generally requires at least 2 characteristic features.

Important features include:

• Six or more café-au-lait macules
• Axillary or inguinal freckling
• Two or more neurofibromas or one plexiform neurofibroma
• Optic pathway glioma
• Two or more Lisch nodules
• Characteristic choroidal abnormalities
• Characteristic osseous lesion
• Pathogenic heterozygous NF1 variant

Café-au-Lait Macules

Typical café-au-lait macules are:

• Flat
• Hyperpigmented
• Well-defined

Diagnostic size thresholds are approximately:

• >5 mm before puberty
• >15 mm after puberty

Six or more are characteristic of NF1.

Axillary and Inguinal Freckling

Freckling in skin-fold areas is highly characteristic.

Common sites include:

• Axilla
• Groin
• Inframammary folds

Neurofibromas

Patients may develop:

• Cutaneous neurofibromas
• Subcutaneous neurofibromas
• Plexiform neurofibromas

A plexiform neurofibroma is particularly characteristic of NF1.

Ophthalmic Manifestations of NF1

Lisch Nodules

Lisch nodules are benign melanocytic hamartomas of the iris.

They appear as:

• Small
• Dome-shaped
• Pigmented iris nodules

They are best detected by:

Slit-lamp examination

Lisch nodules:

• Usually do not affect vision
• Become increasingly common with age
• Are highly characteristic of NF1

Choroidal Abnormalities

Near-infrared fundus imaging may reveal multiple bright choroidal nodules.

These abnormalities are now included among recognized diagnostic features of NF1.

They usually:

• Do not reduce vision
• Are difficult to see on ordinary ophthalmoscopy
• Are readily visible with near-infrared imaging

Optic Pathway Glioma

Optic pathway glioma (OPG) is one of the most important ophthalmic complications of NF1.

It is usually a:

Low-grade pilocytic astrocytoma

and may involve:

• Optic nerve
• Optic chiasm
• Optic tract
• Hypothalamic region

Epidemiology of Optic Pathway Glioma

Radiographic optic pathway gliomas occur in approximately:

15–20% of children with NF1

However, many remain asymptomatic and never require treatment.

Most clinically significant tumors present during childhood.

Clinical Features of Optic Pathway Glioma

Possible manifestations include:

• Reduced visual acuity
• Color vision loss
• Relative afferent pupillary defect
• Optic disc pallor
• Optic disc swelling
• Proptosis
• Strabismus
• Visual field loss
• Nystagmus

Chiasmal or hypothalamic tumors may be associated with:

• Precocious puberty
• Endocrine abnormalities

Plexiform Neurofibroma of the Eyelid

Plexiform neurofibromas commonly involve the:

• Upper eyelid
• Orbit
• Temporal region

Possible findings include:

• Thickened eyelid
• S-shaped upper lid
• Ptosis
• Facial asymmetry
• Proptosis
• Strabismus

These lesions can become extensive and difficult to excise completely.

Sphenoid Wing Dysplasia

Sphenoid wing dysplasia may lead to:

• Enlargement of the orbit
• Pulsatile proptosis
• Facial asymmetry

The temporal lobe may herniate toward the orbit when the sphenoid wing is markedly deficient.

Glaucoma in NF1

Glaucoma may occur, particularly in eyes with:

• Ipsilateral eyelid plexiform neurofibroma
• Orbital involvement
• Anterior segment developmental abnormalities

Congenital or early-onset glaucoma should therefore be considered in affected children.

Other Manifestations of NF1

Neurologic manifestations may include:

• Seizures
• Learning difficulties
• Attention problems
• Gliomas
• Spinal tumors
• Chiari malformation
• Vascular abnormalities

Skeletal Manifestations

Possible findings include:

• Scoliosis
• Long-bone dysplasia
• Tibial bowing
• Pseudarthrosis
• Sphenoid wing dysplasia
• Reduced bone mineral density

Vascular Disease

NF1 can cause vascular abnormalities such as:

• Renal artery stenosis
• Cerebral vasculopathy
• Aneurysms
• Moyamoya arteriopathy

Moyamoya Disease

NF1 is associated with moyamoya arteriopathy, a progressive stenotic disorder affecting intracranial arteries around the Circle of Willis.

Children may present with:

• Transient ischemic attacks
• Stroke
• Seizures
• Weakness

Adults may also develop intracranial hemorrhage.

Hypertension

Hypertension in NF1 may result from:

• Essential hypertension
• Renal artery stenosis
• Pheochromocytoma

Blood pressure should therefore be monitored regularly.

Pheochromocytoma

Symptoms may include:

• Episodic headache
• Palpitations
• Sweating
• Hypertension

Evaluation may include plasma or urinary metanephrines when clinically indicated.

Malignant Peripheral Nerve Sheath Tumor

Patients with NF1 have an increased risk of malignant peripheral nerve sheath tumor (MPNST).

Warning symptoms include:

• Rapid tumor enlargement
• Persistent or increasing pain
• Hardening of a previously soft neurofibroma
• Neurologic deficit

These require urgent evaluation.

NF2-Related Schwannomatosis

The defining tumor predisposition differs substantially from NF1.

Typical tumors include:

• Vestibular schwannomas
• Other cranial nerve schwannomas
• Spinal schwannomas
• Meningiomas
• Ependymomas

Vestibular Schwannomas

The classic hallmark is:

Bilateral vestibular schwannomas

Symptoms include:

• Progressive hearing loss
• Tinnitus
• Imbalance
• Vertigo

Presentation often occurs in adolescence or early adulthood.

Other Cranial Nerve Tumors

Schwannomas may involve other cranial nerves, including:

• CN III
• CN V
• CN VII

These can produce:

• Diplopia
• Ptosis
• Facial sensory abnormalities
• Facial weakness

Ophthalmic Manifestations of NF2

Important ocular abnormalities include:

• Early-onset cataract
• Epiretinal membrane
• Combined hamartoma of retina and RPE
• Retinal abnormalities
• Optic nerve sheath meningioma
• Strabismus
• Cranial nerve palsies

Cataract in NF2

A characteristic finding is a:

Juvenile posterior subcapsular or cortical cataract

Cataract may precede neurologic symptoms and can therefore provide an early clue to the diagnosis.

Epiretinal Membrane

Epiretinal membranes may occur at an unusually young age.

They may cause:

• Metamorphopsia
• Reduced visual acuity
• Macular distortion

Combined Hamartoma of Retina and RPE

This lesion may appear as:

• Elevated gray retinal lesion
• Retinal distortion
• Vascular tortuosity
• Epiretinal fibrosis

It can reduce vision if the macula is involved.

Optic Nerve Sheath Meningioma

NF2 predisposes to meningiomas, including those around the optic nerve.

Possible manifestations include:

• Progressive visual loss
• Optic atrophy
• Optociliary shunt vessels
• Proptosis

Diagnosis

History in NF1

Ask about:

• Café-au-lait lesions
• Skin tumors
• Family history
• Bone abnormalities
• Learning difficulties
• Visual decline
• Proptosis
• Precocious puberty
• Headaches
• Hypertension

History in NF2

Ask about:

• Hearing loss
• Tinnitus
• Balance problems
• Family history
• Diplopia
• Progressive visual loss
• Early cataract
• Neurologic deficits

Ophthalmic Examination

For NF1, examine:

• Visual acuity
• Pupils
• Color vision
• Ocular motility
• Optic discs
• Iris by slit lamp
• Eyelids and orbit
• Fundus

Near-infrared imaging may identify choroidal abnormalities.

Ophthalmic Examination in NF2

Evaluate for:

• Cataract
• Epiretinal membrane
• Retinal hamartoma
• Optic nerve abnormalities
• Strabismus
• Cranial nerve palsies

Genetic Testing

Molecular testing may include:

• NF1 gene sequencing and deletion/duplication analysis
• NF2 gene testing
• Mosaicism assessment when appropriate

Genetic testing is especially useful when:

• Clinical findings are incomplete
• Atypical phenotype is present
• Family planning is being considered

Imaging in NF1

MRI may be indicated when there are:

• Visual abnormalities suggesting optic pathway glioma
• Proptosis
• Neurologic symptoms
• Precocious puberty
• Suspected intracranial or spinal tumor

Routine screening MRI solely to look for an asymptomatic optic pathway glioma is generally not required when reliable ophthalmic surveillance is possible.

MRI Findings in NF1

Possible findings include:

• Optic pathway glioma
• Other low-grade gliomas
• T2-hyperintense focal areas historically called unidentified bright objects

These focal signal abnormalities are particularly common in children.

Imaging in NF2

MRI is central to surveillance because of the high tumor burden.

Serial MRI may assess:

• Vestibular schwannomas
• Meningiomas
• Spinal tumors
• Other cranial nerve schwannomas

Volumetric MRI can be useful for monitoring tumor growth.

Hearing Evaluation in NF2

Assessment may include:

• Pure-tone audiometry
• Speech discrimination testing
• Auditory brainstem response testing

Hearing surveillance is an essential part of management.

Differential Diagnosis of NF1

Important alternatives include:

• Legius syndrome
• McCune-Albright syndrome
• Constitutional café-au-lait pigmentation
• Other RASopathies
• Segmental/mosaic NF1

Legius Syndrome

Legius syndrome is caused by pathogenic variants in:

SPRED1

It can produce:

• Café-au-lait spots
• Axillary or inguinal freckling

but typically lacks:

• Neurofibromas
• Lisch nodules
• Optic pathway gliomas

This is an important differential in young children with pigmentary findings alone.

Differential Diagnosis of NF2

Consider:

• Other forms of schwannomatosis
• Sporadic vestibular schwannoma
• Multiple meningioma syndromes
• Other hereditary tumor-predisposition syndromes

Treatment of NF1

Treatment is individualized according to the complication.

There is no single therapy for NF1 itself.

Optic Pathway Glioma – Observation

Many NF1-associated optic pathway gliomas:

• Grow slowly
• Remain asymptomatic
• Do not require treatment

Treatment is generally based more on:

Documented visual deterioration

than on MRI appearance alone.

Optic Pathway Glioma – Treatment

Treatment is considered when there is:

• Progressive visual loss
• Significant tumor progression with functional impact
• Other clinically important progression

Systemic chemotherapy has traditionally included regimens such as:

• Carboplatin
• Vincristine

Modern targeted treatment, including MEK inhibition, may be considered in selected progressive NF1-associated tumors under specialist care.

Radiation in NF1

Radiotherapy is generally avoided when possible, particularly in children with NF1, because of increased risks of:

• Secondary tumors
• Radiation-induced vasculopathy
• Moyamoya-type vascular disease

Plexiform Neurofibroma

Management may include:

• Observation
• Surgical resection
• Targeted systemic treatment for symptomatic, inoperable lesions

The MEK inhibitor selumetinib is used for selected children with symptomatic, unresectable NF1-associated plexiform neurofibromas.

Treatment of NF2-Related Schwannomatosis

Management may include:

• Observation with serial MRI
• Microsurgery
• Stereotactic radiation in selected patients
• Systemic targeted therapy

Treatment aims to preserve:

• Hearing
• Facial nerve function
• Neurologic function
• Vision

Bevacizumab in NF2

Bevacizumab can be useful in selected patients with progressive vestibular schwannomas, particularly when hearing is deteriorating.

Potential benefits include:

• Tumor shrinkage
• Hearing improvement or stabilization

Treatment requires specialist systemic monitoring.

Cataract Treatment

Visually significant cataract is treated with:

• Cataract extraction
• Intraocular lens implantation when appropriate

Epiretinal Membrane

Observation is appropriate when mild.

Vitrectomy with membrane peeling may be considered when there is significant:

• Visual loss
• Metamorphopsia
• Macular distortion

Multidisciplinary Care

Patients may require involvement of:

• Ophthalmology
• Neuro-ophthalmology
• Neurology
• Neurosurgery
• Neuro-oncology
• Genetics
• ENT/audiology
• Orthopedics
• Dermatology
• Endocrinology
• Cardiology or vascular specialists

Ongoing Ophthalmic Surveillance in NF1

Children require regular ophthalmic examinations, particularly during the years when optic pathway glioma is most likely to become symptomatic.

Monitoring should include:

• Age-appropriate visual acuity
• Pupils
• Color vision when possible
• Ocular alignment
• Optic nerve examination
• Eyelid/orbital assessment

Blood Pressure Monitoring

Patients with NF1 should undergo regular blood pressure assessment because hypertension may indicate:

• Renal artery stenosis
• Pheochromocytoma
• Other vascular disease

Pregnancy Considerations

During pregnancy, women with NF1 may experience:

• Enlargement of existing neurofibromas
• Development of additional neurofibromas

Pregnancy planning should include:

• Genetic counseling
• Assessment of significant tumor burden
• Blood pressure monitoring

Patient Education

Patients and families should seek evaluation for:

• New visual loss
• New strabismus
• Proptosis
• Persistent headache
• New neurologic deficit
• Rapidly enlarging painful neurofibroma
• Hearing loss
• Tinnitus
• Balance problems

Prognosis

NF1

Many patients have relatively mild disease and normal or near-normal life expectancy.

Morbidity depends on complications such as:

• Malignant peripheral nerve sheath tumor
• Severe vascular disease
• CNS tumors
• Large plexiform neurofibromas

NF2-Related Schwannomatosis

NF2 generally causes greater neurologic morbidity because patients frequently develop multiple:

• Schwannomas
• Meningiomas
• Spinal tumors

Modern surveillance, surgery, hearing rehabilitation, and targeted therapy have substantially improved management.

Complications

NF1

Important complications include:

• Visual loss from optic pathway glioma
• Amblyopia
• Glaucoma
• Proptosis
• Skeletal deformity
• Seizures
• Moyamoya disease
• Hypertension
• Malignant peripheral nerve sheath tumor

NF2

Important complications include:

• Hearing loss
• Tinnitus
• Balance dysfunction
• Cranial nerve palsies
• Spinal cord compression
• Visual loss
• Cataract
• Retinal or epiretinal abnormalities

Ophthalmology Pearls

• NF1 = café-au-lait spots + axillary/inguinal freckling + neurofibromas + Lisch nodules + optic pathway glioma.
• Lisch nodules are benign iris hamartomas and usually do not affect vision.
• Choroidal abnormalities detectable by near-infrared imaging are now recognized diagnostic features of NF1.
• The most important vision-threatening lesion in children with NF1 is the optic pathway glioma.
• Most NF1-associated optic pathway gliomas do not require treatment unless visual function deteriorates.
• Plexiform neurofibroma involving the upper eyelid can cause the characteristic S-shaped eyelid deformity.
• NF1 is associated with moyamoya disease, renal artery stenosis, and pheochromocytoma.
• NF2-related schwannomatosis = bilateral vestibular schwannomas until proven otherwise.
• Early cataract, epiretinal membrane, or retinal hamartoma in a young patient may provide an ophthalmic clue to NF2.
• Radiation is generally used cautiously in NF1 because of increased risks of secondary tumors and vasculopathy.
• Both NF1 and NF2 require lifelong multidisciplinary surveillance.

Ophthalmology – Neovascular Glaucoma

Basics

Description

Neovascular glaucoma (NVG) is a severe secondary glaucoma caused by retinal ischemia–driven neovascularization of the iris and anterior chamber angle.

The disease progresses from:

• Iris neovascularization (rubeosis iridis)
• Angle neovascularization
• Formation of a fibrovascular membrane
• Contraction of this membrane
• Progressive peripheral anterior synechiae
• Secondary angle closure
• Markedly elevated intraocular pressure

NVG is often painful and potentially blinding.

Older synonyms include:

• Rubeotic glaucoma
• Hemorrhagic glaucoma
• Congestive glaucoma
• Thrombotic glaucoma

Major Causes

The most important causes are:

• Proliferative diabetic retinopathy
• Ischemic central retinal vein occlusion
• Ocular ischemic syndrome from carotid occlusive disease

Any condition causing sufficiently severe retinal ischemia may produce NVG.

Epidemiology

NVG is relatively uncommon but represents one of the most severe forms of secondary glaucoma.

It occurs predominantly in:

• Older adults
• Patients with diabetes
• Patients with retinal vascular disease
• Patients with severe systemic atherosclerotic disease

The risk is especially high in eyes with:

• Proliferative diabetic retinopathy
• Ischemic CRVO

Risk Factors

Major risk factors include:

• Severe retinal ischemia
• Proliferative diabetic retinopathy
• Ischemic CRVO
• Carotid occlusive disease
• Poorly controlled diabetes
• Hypertension
• Atherosclerosis

Historically, diabetic eyes undergoing extensive intraocular surgery were recognized as being at particularly high risk when severe untreated retinal ischemia was present.

Pathophysiology

The fundamental mechanism is:

Retinal ischemia → angiogenic factor release → anterior segment neovascularization → fibrovascular contraction → angle closure glaucoma

VEGF

Hypoxic retina produces angiogenic mediators, particularly:

Vascular endothelial growth factor (VEGF)

VEGF diffuses through the vitreous and aqueous humor and stimulates formation of abnormal vessels on the:

• Iris
• Pupillary margin
• Anterior chamber angle

Early Stage

Initially, new vessels appear:

• At the pupillary border
• On the anterior iris surface
• Within the anterior chamber angle

At this stage, the angle may still be anatomically open.

IOP may be:

• Normal
• Mildly elevated
• Significantly elevated

Early disease can sometimes be reversed if the underlying ischemic stimulus is treated promptly.

Fibrovascular Membrane Formation

Neovascular tissue is accompanied by fibrovascular proliferation.

This membrane grows across the:

• Iris
• Trabecular meshwork
• Anterior chamber angle

Contraction eventually pulls the peripheral iris anteriorly.

Late Stage

Progressive contraction leads to:

• Peripheral anterior synechiae
• Progressive angle closure
• Severe reduction of aqueous outflow
• Markedly elevated IOP

Once extensive synechial closure develops, regression of vessels alone does not reopen the angle.

Therefore, glaucoma treatment becomes much more difficult.

Etiology

Important causes of retinal ischemia associated with NVG include:

• Central retinal vein occlusion
• Proliferative diabetic retinopathy
• Ocular ischemic syndrome
• Central retinal artery occlusion
• Branch retinal vein occlusion
• Chronic retinal detachment
• Radiation retinopathy
• Sickle cell retinopathy
• Coats disease
• Eales disease
• Retinopathy of prematurity
• Severe chronic ocular inflammation
• Uveitis-glaucoma-hyphema syndrome
• Intraocular tumors
• Carotid-cavernous fistula
• Giant cell arteritis
• Takayasu arteritis
• Anterior segment ischemia
• Severe ocular trauma

Intraocular Tumors

Rarely, rubeosis may develop secondary to:

• Retinoblastoma in children
• Choroidal melanoma
• Other intraocular tumors

When the fundus cannot be visualized, an occult intraocular tumor must be considered before performing destructive glaucoma procedures.

Associated Systemic Conditions

Common systemic associations include:

• Diabetes mellitus
• Hypertension
• Hyperlipidemia
• Atherosclerotic cardiovascular disease
• Carotid artery disease

Clinical Stages

NVG can be considered in three broad stages.

Stage 1 – Rubeosis Iridis

Features:

• Fine iris neovascularization
• Usually begins at the pupillary margin
• Angle may remain open
• IOP may still be normal

This is the ideal stage for intervention.

Stage 2 – Open-Angle NVG

Features include:

• Neovascularization of the angle
• Fibrovascular membrane over the trabecular meshwork
• Increasing IOP
• Angle still partly open

This stage may still respond to rapid retinal ischemia treatment and IOP-lowering therapy.

Stage 3 – Synechial Angle Closure

Features include:

• Extensive peripheral anterior synechiae
• Closed angle
• Very high IOP
• Pain
• Corneal edema
• Marked visual loss

At this stage, glaucoma surgery is frequently required.

Diagnosis

History

Typical symptoms include:

• Painful red eye
• Ocular pressure sensation
• Headache
• Photophobia
• Decreased vision
• Halos around lights

Some patients may initially be asymptomatic when only iris neovascularization is present.

External and Anterior Segment Examination

Possible findings include:

• Conjunctival injection
• Ciliary flush
• Corneal edema
• Shallow or normal anterior chamber depending on stage
• Anterior chamber cells and flare
• Hyphema

Rubeosis Iridis

The earliest iris finding is often:

Fine abnormal vessels at the pupillary margin

These vessels:

• Are irregular
• Cross normal iris architecture
• Extend onto the anterior iris surface

They should not be confused with normal radial iris vessels.

Gonioscopy

Gonioscopy is essential.

Look for:

• Fine neovascular vessels crossing the scleral spur
• Neovascularization of the trabecular meshwork
• Peripheral anterior synechiae
• Extent of angle closure

Angle neovascularization can precede obvious iris neovascularization.

Hyphema

Fragile new vessels may bleed spontaneously, causing:

• Microhyphema
• Gross hyphema

Hyphema can further increase IOP.

Intraocular Pressure

IOP can be:

• Normal in very early rubeosis
• Moderately elevated in open-angle disease
• Extremely elevated after synechial angle closure

Posterior Segment Examination

A dilated retinal examination should identify the ischemic cause.

Central Retinal Vein Occlusion

Features suggesting CRVO include:

• Dilated tortuous retinal veins
• Widespread retinal hemorrhages
• Cotton-wool spots
• Disc edema
• Macular edema

Extensive ischemia greatly increases NVG risk.

Proliferative Diabetic Retinopathy

Look for:

• Neovascularization of the disc
• Neovascularization elsewhere
• Preretinal hemorrhage
• Vitreous hemorrhage
• Extensive capillary nonperfusion

Ocular Ischemic Syndrome

Possible findings include:

• Midperipheral dot-blot hemorrhages
• Narrow retinal arteries
• Dilated but often not markedly tortuous veins
• Delayed retinal arterial filling
• Iris neovascularization
• Ocular pain

Severe carotid stenosis should be investigated.

Central Retinal Artery Occlusion

Look for:

• Retinal whitening
• Cherry-red spot
• Attenuated retinal arteries

NVG is less common after CRAO than after ischemic CRVO but can occur when widespread ocular ischemia persists.

Diagnostic Testing

Fluorescein Angiography

Fluorescein angiography can identify:

• Areas of retinal capillary nonperfusion
• Retinal neovascularization
• Leakage
• Severity of ischemia

It can be particularly useful in:

• CRVO
• Diabetic retinopathy
• Ocular ischemic syndrome

OCT

OCT may be useful for evaluating:

• Macular edema
• Diabetic macular disease
• Retinal structural damage

It does not replace fluorescein angiography for assessing widespread retinal perfusion.

B-Scan Ultrasonography

B-scan is useful when the fundus cannot be seen because of:

• Dense cataract
• Vitreous hemorrhage
• Corneal opacity

It can help identify:

• Retinal detachment
• Intraocular tumor
• Other posterior segment abnormalities

Carotid Evaluation

When ocular ischemic syndrome or arterial occlusive disease is suspected, evaluation may include:

• Carotid duplex ultrasonography
• CT angiography
• MR angiography

Systemic vascular referral may be necessary.

Laboratory Evaluation

Laboratory testing depends on the underlying cause.

Possible tests include:

• Fasting glucose
• HbA1c
• Lipid profile
• Blood pressure assessment

In selected patients:

• ESR
• CRP
• Platelet count

may be appropriate when giant cell arteritis is suspected.

Younger patients with unusual retinal vascular occlusion may require targeted evaluation for:

• Hypercoagulable states
• Hyperviscosity disorders
• Systemic inflammatory disease

Follow-Up After CRVO

Eyes with CRVO require close surveillance for:

• Iris neovascularization
• Angle neovascularization
• Conversion to a more ischemic phenotype

The highest risk period is within the first several months.

Monthly anterior segment examination and gonioscopy during the early high-risk period is often appropriate, especially in ischemic or indeterminate CRVO.

Differential Diagnosis

Important differential diagnoses include:

• Uveitic glaucoma
• Fuchs uveitis syndrome
• Primary angle-closure glaucoma
• Posner-Schlossman syndrome
• Traumatic glaucoma
• Ghost-cell glaucoma
• Hemolytic glaucoma

The presence of iris or angle neovascularization strongly supports NVG.

Treatment Principles

Treatment has two simultaneous goals:

1. Eliminate the retinal ischemic stimulus
2. Lower intraocular pressure and control pain

Treating IOP alone without treating retinal ischemia usually fails.

Panretinal Photocoagulation

Panretinal photocoagulation (PRP) is the definitive treatment for retinal ischemia when sufficient retina can be visualized.

PRP reduces the ischemic retinal tissue producing VEGF.

It can cause regression of:

• Iris neovascularization
• Angle neovascularization

and helps reduce recurrent neovascularization.

Anti-VEGF Therapy

Intravitreal anti-VEGF treatment produces rapid regression of anterior segment neovascularization.

Common agents include:

• Bevacizumab
• Ranibizumab
• Aflibercept

Role of Anti-VEGF

Anti-VEGF therapy:

• Acts rapidly
• Reduces iris neovascularization
• Reduces angle neovascularization
• Reduces bleeding
• May facilitate subsequent glaucoma surgery

However:

Anti-VEGF therapy is temporary and does not replace PRP when retinal ischemia is present and treatable.

The ischemic retina continues to produce VEGF once the drug effect disappears.

PRP + Anti-VEGF

A common modern strategy is:

Anti-VEGF for rapid vessel regression + PRP for durable treatment of the ischemic drive

This combination is particularly valuable when there is:

• Florid rubeosis
• Hyphema
• Very active neovascularization

When PRP Cannot Initially Be Performed

PRP may be impossible because of:

• Dense vitreous hemorrhage
• Cataract
• Corneal edema
• Poor pupillary dilation

Options may include:

• Anti-VEGF as temporary control
• Pars plana vitrectomy
• Endolaser PRP during vitrectomy

depending on the underlying condition.

Medical IOP Treatment

Aqueous suppressants are preferred.

Useful medications include:

• Beta-blockers
• Alpha-2 agonists such as brimonidine
• Topical carbonic anhydrase inhibitors
• Oral acetazolamide when appropriate

Prostaglandin Analogs