Ophthalmology – Ocular Ischemic Syndrome

Basics

Description

Ocular ischemic syndrome (OIS) is a spectrum of anterior and posterior segment abnormalities caused by chronic ocular hypoperfusion, most commonly from severe carotid occlusive disease.

It may affect:

• Retina
• Choroid
• Optic nerve
• Iris
• Ciliary body
• Anterior segment
• Orbit in very severe cases

The most common symptoms are:

• Progressive monocular visual loss
• Ocular or orbital pain

OIS is particularly important because it is a marker of severe systemic vascular disease and is associated with increased risk of:

• Stroke
• Myocardial infarction
• Cardiovascular death

Epidemiology

OIS is relatively uncommon but probably underdiagnosed.

Estimated incidence is approximately:

7–8 cases per million persons per year

Typical demographics include:

• Mean age around 65 years
• Usually age 50–80 years
• Male predominance, reflecting atherosclerotic vascular disease

Bilateral disease occurs in a minority of patients.

Risk Factors

Major risk factors are those for systemic atherosclerosis, including:

• Hypertension
• Diabetes mellitus
• Hyperlipidemia
• Smoking
• Coronary artery disease
• Peripheral vascular disease
• Previous TIA
• Previous stroke
• Advanced age

Pathophysiology

The fundamental mechanism is:

Reduced carotid/ophthalmic arterial flow + inadequate collateral circulation → chronic ocular hypoperfusion

This results in:

• Retinal ischemia
• Choroidal ischemia
• Ciliary body ischemia
• Anterior segment ischemia
• VEGF production
• Retinal and iris neovascularization

Severe ischemia may ultimately produce:

• Neovascular glaucoma
• Retinal vascular insufficiency
• Hypotony
• Profound visual loss

Etiology

Carotid Occlusive Disease

The most common cause is severe atherosclerotic disease of the carotid circulation.

Most commonly involved:

1. Internal carotid artery
2. Common carotid artery
3. Less commonly external carotid collateral pathways

Historically, OIS is most often associated with very high-grade carotid stenosis or complete occlusion.

However, the clinical severity depends not only on the percentage of stenosis but also on:

Adequacy of collateral circulation

Therefore, OIS can occasionally occur with less dramatic stenosis when collateral flow is poor.

Other Causes

Less common causes include:

• Ophthalmic artery occlusive disease
• Giant cell arteritis
• Takayasu arteritis
• Aortic arch disease
• Other large-vessel vasculitis
• Severe systemic hypotension
• Rare hypercoagulable or vaso-occlusive disorders

Commonly Associated Conditions

Frequently associated systemic diseases include:

• Hypertension
• Diabetes mellitus
• Coronary artery disease
• Previous stroke or TIA
• Peripheral arterial disease
• Dyslipidemia

Diagnosis

OIS should be suspected when an older patient with vascular risk factors develops:

• Unilateral progressive visual loss
• Ocular ache
• Midperipheral retinal hemorrhages
• Narrow retinal arteries
• Iris neovascularization
• Delayed choroidal filling on angiography

History

Visual Loss

Visual loss is the most common symptom.

It may be:

• Gradual over weeks to months
• Progressive
• Occasionally abrupt

Many patients present with visual acuity worse than:

20/60

Visual loss may arise from:

• Macular ischemia
• Retinal ischemia
• Neovascular glaucoma
• Cataract
• Optic nerve ischemia
• Retinal artery occlusion

Transient Monocular Visual Loss

Some patients experience:

Amaurosis fugax

This may present as:

• Transient dimming
• Curtain-like visual loss
• Brief monocular blindness

This should raise concern for significant carotid vascular disease.

Delayed Recovery After Bright Light

A characteristic symptom is:

Prolonged recovery of vision after exposure to bright light

The ischemic retina requires abnormally long to recover after photoreceptor bleaching.

This is an important clue to ocular hypoperfusion.

Ocular Pain

Approximately one-third to nearly one-half of patients experience:

Dull ocular or periorbital pain

Sometimes termed:

Ocular angina

Pain may result from:

• Ocular ischemia
• Elevated IOP from neovascular glaucoma

It is often described as:

• Dull
• Constant
• Periorbital or brow ache

Anterior Segment Findings

Possible findings include:

• Conjunctival injection
• Episcleral injection
• Corneal edema
• Descemet folds
• Mild anterior chamber inflammation
• Iris atrophy
• Iris neovascularization
• Posterior synechiae
• Anterior synechiae
• Cataract

Anterior Chamber Inflammation

Mild anterior uveitis may occur.

Typical pattern:

• Relatively prominent flare
• Fewer cells

This reflects ischemic disruption of the blood-aqueous barrier.

Iris Neovascularization

Rubeosis iridis is a major finding.

It results from:

Retinal ischemia → VEGF production → anterior segment neovascularization

It may progress to:

• Angle neovascularization
• Peripheral anterior synechiae
• Neovascular glaucoma

Intraocular Pressure

IOP may be:

• Elevated
• Normal
• Low

Elevated IOP

Usually due to:

• Neovascular glaucoma

Low IOP

May result from:

Ciliary body hypoperfusion and reduced aqueous production

This is an important distinction from many other ischemic retinal conditions.

Hypotony

Severe ciliary body ischemia may cause hypotony.

Consequences include:

• Corneal decompensation
• Cataract
• Hypotony maculopathy
• Progressive structural damage

Pupils

Possible abnormalities include:

• RAPD
• Sluggish response
• Semidilated pupil

depending on the degree of retinal and optic nerve ischemia.

Posterior Segment Findings

Posterior segment abnormalities are extremely important.

Typical findings include:

• Narrowed retinal arteries
• Dilated but relatively non-tortuous retinal veins
• Midperipheral retinal hemorrhages
• Microaneurysms
• Cotton-wool spots
• Retinal neovascularization
• Optic disc neovascularization
• Choroidal ischemia

Retinal Hemorrhages

A classic pattern is:

Dot-blot hemorrhages predominantly in the midperipheral retina

This contrasts with CRVO, where hemorrhages are often:

• More diffuse
• Present in all quadrants
• Associated with more tortuous veins

Retinal Veins

OIS typically shows:

Dilated but not markedly tortuous veins

This is an important clue distinguishing OIS from CRVO.

Microaneurysms

Microaneurysms are often:

• Numerous
• Midperipheral

They may become particularly apparent on fluorescein angiography.

Retinal Arterial Pulsations

Spontaneous retinal arterial pulsation may occur because ocular perfusion pressure is critically low.

Cotton-Wool Spots

Cotton-wool spots may occur from focal retinal nerve fiber layer ischemia.

Choroidal Ischemia

Possible findings include:

• Patchy choroidal nonperfusion
• Peripheral wedge-shaped chorioretinal atrophy
• Delayed choroidal filling on angiography

Retinal and Disc Neovascularization

Chronic retinal ischemia can lead to:

• Neovascularization of the disc
• Neovascularization elsewhere
• Vitreous hemorrhage
• Neovascular glaucoma

Central Retinal Artery Occlusion

A cherry-red spot may occasionally occur if OIS is complicated by:

• Central retinal artery occlusion
• Severe acute arterial hypoperfusion

Orbital Infarction Syndrome

An extreme form of ischemia may involve both:

• Intraocular tissues
• Orbital tissues

Features may include:

• Severe orbital pain
• Ptosis
• Ophthalmoplegia
• Proptosis
• Corneal hypoesthesia
• Intraocular inflammation
• Hypotony

This represents severe compromise of orbital blood supply.

Systemic Examination

Examine for evidence of vascular disease.

Assessment should include:

• Blood pressure
• Peripheral pulses
• Carotid auscultation
• Cardiac examination

However, absence of a carotid bruit does not exclude severe carotid stenosis.

Fluorescein Angiography

FA is one of the most useful ocular diagnostic tests.

Delayed Choroidal Filling

The most characteristic finding is:

Delayed or patchy choroidal filling

This is one of the most specific angiographic signs of OIS.

Prolonged Arteriovenous Transit Time

A highly sensitive finding is:

Prolonged retinal arteriovenous transit

There may be markedly delayed passage of fluorescein from the retinal arteries into the veins.

Additional FA Findings

Other findings include:

• Retinal vascular staining
• Arterial wall staining
• Capillary nonperfusion
• Microaneurysms
• Disc leakage
• Macular leakage
• Slow leading edge of arterial dye

OCT

OCT may demonstrate:

• Macular edema
• Retinal thinning from chronic ischemia
• Inner retinal atrophy
• Secondary epiretinal changes

Macular edema in OIS is less common than in CRVO or diabetic retinopathy.

OCT Angiography

OCTA may help demonstrate:

• Reduced retinal capillary density
• Macular nonperfusion

However, it does not replace systemic vascular imaging.

Indocyanine Green Angiography

ICG may show:

• Delayed arm-to-choroid circulation
• Slow choroidal filling
• Abnormal watershed zones

It can further demonstrate choroidal vascular insufficiency.

Carotid Duplex Ultrasonography

Carotid Doppler ultrasound is commonly the initial noninvasive vascular test.

It evaluates:

• Degree of stenosis
• Flow velocity
• Plaque morphology
• Hemodynamics

Limitations include:

• Calcified plaque
• Tortuous vessels
• High cervical lesions
• Operator dependence

CTA and MRA

CT angiography and MR angiography provide detailed evaluation of:

• Carotid arteries
• Intracranial circulation
• Collateral circulation

These are particularly useful when:

• Duplex findings are inconclusive
• Surgical intervention is being considered
• Intracranial disease is suspected

Ophthalmic Artery Doppler

Retrobulbar Doppler may show:

Reversal of ophthalmic artery flow

This is a strong indicator of severe ipsilateral carotid occlusive disease with collateralization through the external carotid system.

Catheter Angiography

Digital subtraction angiography provides highly detailed vascular imaging but is invasive.

It is generally reserved for cases in which:

• Endovascular intervention is being considered
• Noninvasive imaging is inconclusive

Electroretinography

ERG may demonstrate impairment of both:

• Outer retina → reduced a-wave
• Inner retina → reduced b-wave

This reflects generalized retinal ischemia.

It is rarely needed for routine diagnosis.

Visual-Evoked Potentials

VEP may show:

• Reduced amplitude
• Increased latency

but is nonspecific and rarely central to diagnosis.

Giant Cell Arteritis Evaluation

If OIS-like findings occur in a patient with possible GCA, urgently consider:

• ESR
• CRP
• CBC with platelet count

Particularly ask about:

• New headache
• Jaw claudication
• Scalp tenderness
• Polymyalgia symptoms
• Constitutional symptoms

Differential Diagnosis

The two most important retinal mimics are:

• Central retinal vein occlusion
• Diabetic retinopathy

OIS vs Central Retinal Vein Occlusion

OIS typically shows:

• Narrow retinal arteries
• Dilated but minimally tortuous veins
• Midperipheral dot-blot hemorrhages
• Delayed choroidal filling
• Prolonged AV transit
• Possible low IOP

CRVO typically shows:

• Markedly dilated tortuous veins
• Extensive hemorrhage in all quadrants
• Disc edema
• Frequent macular edema
• Primarily venous outflow obstruction

OIS vs Diabetic Retinopathy

OIS is commonly:

• Unilateral or markedly asymmetric
• Associated with delayed choroidal filling
• Associated with midperipheral hemorrhage predominance

Diabetic retinopathy is usually:

• Bilateral
• More symmetric
• Characterized by posterior-pole microaneurysms and hemorrhages
• Often associated with hard exudates and diabetic macular edema

However, severe carotid disease can make diabetic retinopathy highly asymmetric.

Additional Differential Diagnosis

Consider:

• Ischemic CRVO
• Proliferative diabetic retinopathy
• Hypertensive retinopathy
• Retinal artery occlusion
• Giant cell arteritis
• Takayasu arteritis
• Hyperviscosity retinopathy
• Neovascular glaucoma from another cause

Treatment Principles

Management has three major objectives:

1. Restore or optimize ocular/systemic perfusion where possible
2. Treat retinal ischemia and neovascularization
3. Treat secondary complications such as neovascular glaucoma

Systemic vascular evaluation is essential because OIS often indicates potentially life-threatening vascular disease.

Systemic Vascular Management

All patients should undergo urgent medical evaluation for:

• Carotid disease
• Coronary artery disease
• Stroke risk
• Diabetes
• Hypertension
• Dyslipidemia

Management may include:

• Antiplatelet therapy when appropriate
• Statin therapy
• Blood pressure optimization
• Diabetes control
• Smoking cessation
• Weight management
• Exercise and dietary modification

These decisions should be coordinated with the appropriate medical or vascular team.

Carotid Revascularization

Carotid Endarterectomy

Carotid endarterectomy (CEA) may be indicated in selected patients with significant carotid stenosis, especially when the patient is symptomatic and operative risk is acceptable.

The decision depends on:

• Degree of stenosis
• Whether stenosis is symptomatic
• Overall neurologic risk
• Life expectancy
• Surgical risk
• Vascular anatomy

Because treatment guidelines evolve, these patients require vascular or stroke-specialist assessment rather than relying solely on a fixed percentage threshold.

Carotid Artery Stenting

Carotid artery stenting may be considered when:

• CEA carries excessive risk
• Anatomy is unfavorable for surgery
• Other vascular considerations favor an endovascular approach

Effect of Revascularization on the Eye

Improved carotid flow may:

• Improve ocular perfusion
• Reduce ischemic symptoms
• Reduce neovascular drive

The benefit is generally greatest before irreversible retinal damage or advanced neovascular glaucoma has developed.

Visual recovery is limited once severe retinal or optic nerve ischemia is established.

Panretinal Photocoagulation

PRP is used when there is retinal or anterior segment neovascularization from ischemia.

It can reduce VEGF production and help cause regression of:

• Iris neovascularization
• Disc neovascularization
• Retinal neovascularization

However, PRP may be less effective in OIS than in proliferative diabetic retinopathy because the entire ocular circulation is hypoperfused.

Anti-VEGF Therapy

Intravitreal anti-VEGF agents may produce rapid regression of:

• Iris neovascularization
• Angle neovascularization
• Retinal neovascularization

They may also help macular edema in selected patients.

However:

Anti-VEGF is an adjunct, not treatment of the underlying carotid hypoperfusion.

Its effect on neovascularization may be temporary unless the ischemic drive is also addressed.

Anterior Uveitis

Mild ischemic anterior inflammation may be treated with:

• Topical corticosteroids
• Cycloplegics

Cycloplegics can:

• Reduce ciliary spasm
• Improve pain
• Prevent posterior synechiae

Neovascular Glaucoma

NVG is a major vision-threatening complication.

Treatment includes:

• Anti-VEGF
• PRP when possible
• IOP-lowering therapy
• Anti-inflammatory treatment
• Glaucoma surgery when necessary

IOP-Lowering Medications

Aqueous suppressants are generally preferred:

• Beta-blockers
• Alpha-2 agonists
• Topical carbonic anhydrase inhibitors

Systemic carbonic anhydrase inhibitors may be considered in selected severe cases if medically appropriate.

Pilocarpine

Pilocarpine should generally be avoided in neovascular or inflamed eyes because it:

• Is usually ineffective in synechial angle closure
• Can worsen inflammation
• May increase discomfort

Prostaglandin Analogs

Prostaglandin analogs can lower IOP, but historically have been used cautiously in markedly inflamed ischemic eyes.

In modern practice they may still be considered when additional IOP reduction is needed and inflammation is controlled.

They are not absolutely contraindicated solely because OIS is present.

Glaucoma Surgery

If NVG remains uncontrolled, options include:

• Glaucoma drainage device
• Trabeculectomy in selected quiet eyes
• Cyclophotocoagulation

Tube shunts are often favored in eyes with active or previously active neovascularization.

Cyclodestructive Treatment

Cyclophotocoagulation may be especially useful when:

• Visual potential is poor
• Pain is significant
• IOP is refractory
• Incisional surgery is unlikely to succeed

Hypotony

If IOP is already low because of severe ciliary body ischemia:

IOP-lowering therapy should not be given simply because neovascularization is present.

Treatment must be tailored to the actual pressure and mechanism.

Referral

OIS should trigger multidisciplinary evaluation.

Appropriate referrals may include:

• Retina specialist
• Glaucoma specialist
• Primary care/internal medicine
• Neurology or stroke service
• Vascular surgery
• Cardiology

Urgency

New OIS is not merely an ophthalmic problem.

Because severe carotid disease may be present, patients need prompt systemic vascular assessment.

Urgency is particularly high with:

• Amaurosis fugax
• Recent neurologic symptoms
• Acute visual loss
• Known severe carotid stenosis

Follow-Up

Frequency depends on:

• Retinal ischemia
• Presence of neovascularization
• IOP
• Visual acuity
• Treatment status

Patients with active neovascularization or NVG require close follow-up.

Monitor:

• Iris
• Angle by gonioscopy
• IOP
• Retina
• Optic disc
• Macula

Patient Education

Patients should understand that OIS may represent:

Severe systemic vascular disease

They should seek urgent care for symptoms such as:

• Sudden weakness or numbness
• Facial droop
• Speech difficulty
• Sudden monocular visual loss
• Chest pain
• Severe new neurologic symptoms

Systemic Risk Modification

Long-term care should emphasize:

• Smoking cessation
• Diabetes control
• Blood pressure control
• Lipid management
• Appropriate antiplatelet/statin therapy
• Cardiovascular follow-up

Extreme lowering of systemic blood pressure should be avoided in patients with critically impaired ocular perfusion unless medically necessary.

Prognosis

Visual Prognosis

Visual prognosis is generally:

Guarded to poor

because presentation often occurs after substantial chronic ischemic damage.

Poor prognostic factors include:

• Severe visual loss at presentation
• Iris neovascularization
• Neovascular glaucoma
• Extensive retinal ischemia
• Advanced carotid disease

Once profound ischemic retinal damage has occurred, restoring carotid flow may not restore vision.

Systemic Prognosis

The systemic prognosis is also serious.

OIS is associated with substantial risk of:

• Stroke
• Myocardial infarction
• Cardiovascular death

Therefore, identifying OIS can be life-saving even when ocular visual recovery is limited.

Complications

Ocular complications include:

• Neovascular glaucoma
• Retinal neovascularization
• Vitreous hemorrhage
• Macular edema
• Cataract
• Hypotony
• Corneal decompensation
• Retinal artery occlusion
• Severe permanent visual loss

Systemic complications include:

• Cerebral infarction
• TIA
• Myocardial infarction
• Cardiovascular death

Ophthalmology Pearls

• OIS = chronic ocular hypoperfusion, most commonly from severe carotid occlusive disease.
• Classic presentation: progressive monocular visual loss + dull ocular/orbital pain in an older patient with vascular risk factors.
• Retinal findings classically include narrow arteries, dilated but relatively non-tortuous veins, and midperipheral dot-blot hemorrhages.
• Delayed patchy choroidal filling on fluorescein angiography is one of the most specific signs.
• Prolonged arteriovenous transit time is highly sensitive.
• IOP may be high from neovascular glaucoma or low from ciliary body ischemia.
• Rubeosis in OIS results from severe ischemia and may progress to neovascular glaucoma.
• Unlike CRVO, OIS veins are generally not markedly tortuous, and hemorrhages are often concentrated in the midperiphery.
• Carotid duplex is a common initial vascular study, with CTA/MRA used for further anatomic assessment.
• Anti-VEGF and PRP treat ocular neovascularization but do not correct the underlying carotid hypoperfusion.
• Carotid revascularization is most likely to benefit ocular perfusion before advanced irreversible retinal damage or NVG develops.
• OIS is a marker of potentially life-threatening vascular disease; systemic stroke and cardiovascular evaluation is mandatory.

Ophthalmology – Ocular Hypertension

Basics

Description

Ocular hypertension (OHT) refers to consistently elevated intraocular pressure (IOP) in an eye with:

• Open anterior chamber angles
• No glaucomatous optic nerve damage
• No glaucomatous retinal nerve fiber layer loss
• No corresponding visual field defect
• No secondary ocular cause explaining the elevated IOP

Historically, OHT has often been defined as:

IOP >21 mmHg

However, 21 mmHg is a statistical threshold rather than a strict biologic cutoff.

The key distinction is:

Ocular hypertension = elevated IOP without glaucoma damage.

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Epidemiology

Ocular hypertension is relatively common.

Estimated prevalence among adults older than 40 years is approximately:

4–7%

Only a proportion of patients with OHT eventually develop primary open-angle glaucoma.

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Clinical Importance

OHT itself does not mean that glaucoma is present.

However:

Elevated IOP is the most important modifiable risk factor for developing primary open-angle glaucoma.

Management therefore focuses on determining:

• How high the individual patient’s risk is
• Whether preventive treatment is justified
• How closely the patient should be monitored

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Risk of Conversion to Glaucoma

The landmark Ocular Hypertension Treatment Study (OHTS) identified several major predictors of progression from OHT to primary open-angle glaucoma.

Important risk factors include:

• Increasing age
• Higher baseline IOP
• Larger vertical cup-to-disc ratio
• Higher visual field pattern standard deviation
• Thinner central corneal thickness

The greater the number and severity of these factors, the greater the risk of conversion.

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Central Corneal Thickness

Central corneal thickness is particularly important.

Thin cornea

A thin cornea may:

• Cause Goldmann applanation tonometry to underestimate IOP
• Be associated with a higher independent risk of glaucoma development

Thick cornea

A thick cornea may:

• Produce a higher measured IOP
• Make the apparent ocular hypertension less concerning in some patients

However:

There is no universally reliable formula for mathematically “correcting” IOP according to corneal thickness.

CCT should be interpreted as part of the overall risk profile.

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Additional Risk Considerations

Other factors that may influence the decision to treat include:

• Strong family history of glaucoma
• African ancestry
• Long life expectancy
• Progressive increase in optic nerve cupping
• Disc hemorrhage
• Very high untreated IOP
• Thin cornea
• Suspicious OCT changes
• Reduced ability to attend reliable follow-up

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Genetics

There is no single genetic marker that defines ocular hypertension.

OHT and primary open-angle glaucoma likely share a complex polygenic susceptibility.

Family history remains clinically useful even when molecular testing is not performed.

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Pathophysiology

The exact reason some patients tolerate elevated IOP without optic nerve damage while others develop glaucoma is incompletely understood.

Important factors probably include differences in:

• Lamina cribrosa anatomy
• Optic nerve susceptibility
• Ocular blood flow
• Connective tissue properties
• Retinal ganglion cell resilience
• IOP magnitude and fluctuation

OHT may therefore be considered a risk state, not a disease with established neural injury.

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Etiology

Primary ocular hypertension has no identifiable secondary cause.

Before making the diagnosis, exclude:

• Angle closure
• Pigment dispersion
• Pseudoexfoliation
• Uveitis
• Steroid response
• Ocular trauma
• Previous surgery
• Neovascularization
• Lens-related secondary glaucoma

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Associated Conditions

OHT is associated primarily with:

• Increased risk of primary open-angle glaucoma
• Thick or thin central corneal thickness affecting interpretation of IOP

Some patients have no other ocular or systemic abnormality.

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Diagnosis

OHT is a diagnosis of exclusion.

The patient must have elevated IOP but no demonstrable glaucomatous structural or functional damage.

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History

Patients are usually:

Asymptomatic

Ask about:

• Previous IOP measurements
• Family history of glaucoma
• Steroid use
• Ocular trauma
• Previous ocular surgery
• Uveitis
• Migraine
• Sleep apnea
• Systemic hypertension
• Diabetes
• Medication history

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Visual Symptoms

OHT itself does not usually cause:

• Pain
• Redness
• Visual field loss
• Reduced visual acuity

Symptoms suggest another diagnosis or a complication.

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Examination

Intraocular Pressure

Elevated IOP should be confirmed on more than one occasion whenever practical.

Important considerations include:

• Time of day
• Measurement technique
• Corneal thickness
• Corneal biomechanics
• Patient squeezing
• Breath-holding
• Measurement error

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Diurnal Variation

IOP varies throughout the day.

A patient with apparently mild OHT may have higher IOP outside usual clinic hours.

Repeated measurements at different times may occasionally be useful when:

• IOP is highly variable
• Optic nerve findings are suspicious
• Progression occurs despite apparently acceptable readings

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Gonioscopy

Gonioscopy is essential.

OHT should have:

• Open angles
• No significant peripheral anterior synechiae
• No secondary angle abnormality

Gonioscopy helps exclude:

• Chronic angle closure
• Pigment dispersion
• Pseudoexfoliation
• Angle recession
• Neovascularization
• Inflammatory abnormalities

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Optic Nerve Examination

The optic nerve should show no definite glaucomatous damage.

Assess:

• Cup-to-disc ratio
• Vertical cupping
• Neuroretinal rim thickness
• Rim notching
• Disc hemorrhage
• RNFL defects
• Inter-eye asymmetry

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Suspicious Optic Nerve

Findings such as:

• Focal rim thinning
• Inferotemporal or superotemporal notching
• RNFL wedge defect
• Disc hemorrhage

raise concern that the patient may already have:

Early glaucoma rather than isolated OHT.

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Optical Coherence Tomography

OCT should assess:

• Peripapillary RNFL
• Macular ganglion cell complex
• Ganglion cell–inner plexiform layer
• Optic nerve head

In true OHT, structural testing should remain within expected normal limits and stable over time.

Serial OCT is more useful than a single scan.

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Optic Disc Photography

Baseline optic disc photographs are valuable for detecting future change.

They can document:

• Cup enlargement
• Rim thinning
• New disc hemorrhage
• RNFL changes

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Visual Field Testing

Standard automated perimetry is required to establish that there is no functional glaucomatous loss.

Typical baseline testing includes:

• 24-2
• 24-2C depending on availability

If central damage is suspected, a:

• 10-2 visual field

may be useful.

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Pachymetry

Central corneal thickness should be measured in essentially all patients with OHT.

This helps with:

• IOP interpretation
• Risk stratification

Thin CCT is an important predictor of conversion to glaucoma.

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Differential Diagnosis

Important alternatives include:

• Primary open-angle glaucoma
• Secondary open-angle glaucoma
• Chronic angle-closure glaucoma
• Steroid-induced ocular hypertension
• Pigmentary glaucoma
• Pseudoexfoliative glaucoma
• Uveitic glaucoma
• Angle-recession glaucoma

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Ocular Hypertension vs Primary Open-Angle Glaucoma

Ocular Hypertension

• Elevated IOP
• Open angle
• No optic nerve damage
• No RNFL loss
• No visual field defect

Primary Open-Angle Glaucoma

• Open angle
• Characteristic optic nerve/RNFL damage
• Corresponding visual field loss may be present
• IOP may be elevated or normal

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Treatment Principles

Not every patient with OHT requires treatment.

Management may consist of:

• Observation
• Medical therapy
• Laser trabeculoplasty

The decision depends on the estimated risk of developing glaucoma.

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OHTS Findings

The Ocular Hypertension Treatment Study showed that lowering IOP reduces the risk of conversion to glaucoma.

At approximately 5 years:

• Untreated patients developed glaucoma at roughly 9.5%
• Treated patients developed glaucoma at roughly 4.4%

Therefore:

IOP reduction approximately halved the relative risk of developing glaucoma.

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Important Interpretation

The absolute benefit of treatment is greatest in:

High-risk patients

Low-risk patients may reasonably be observed because many never develop glaucoma.

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Initial Target IOP

In OHTS, treatment aimed for approximately:

• At least 20% reduction from baseline IOP
• IOP of approximately 24 mmHg or lower

This is a useful starting concept, but modern targets should be individualized.

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When Observation Is Reasonable

Observation is often appropriate when:

• IOP is only mildly elevated
• CCT is relatively thick
• Optic nerve is healthy
• OCT is normal
• Visual fields are normal
• Patient is young but low risk
• Reliable follow-up is possible

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When Treatment Is Favored

Treatment should be considered when there is:

• Very high IOP
• Thin CCT
• Large cup-to-disc ratio
• Suspicious optic nerve appearance
• Strong family history
• Older age
• Long expected lifetime risk
• Progressive structural change
• High calculated OHTS risk
• Difficulty ensuring reliable follow-up

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Selective Laser Trabeculoplasty

Selective laser trabeculoplasty (SLT) is now an important first-line treatment option.

Advantages include:

• Effective IOP reduction
• Avoidance or delay of daily medication
• Minimal systemic effects
• Repeatability in selected patients

It may be used:

• As primary treatment
• As adjunctive treatment

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Prostaglandin Analogs

Common first-line topical agents include:

• Latanoprost
• Travoprost
• Bimatoprost
• Tafluprost

Advantages include:

• Strong IOP-lowering effect
• Once-daily dosing
• Minimal systemic adverse effects

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Beta-Blockers

Examples include:

• Timolol
• Betaxolol

They are effective but should be used cautiously in patients with:

• Asthma
• COPD
• Bradycardia
• Heart block
• Significant hypotension

They are no longer automatically preferred over prostaglandin analogs or SLT as first-line therapy.

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Topical Carbonic Anhydrase Inhibitors

Examples include:

• Dorzolamide
• Brinzolamide

These may be used as:

• Monotherapy
• Adjunctive therapy

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Alpha-2 Agonists

Example:

• Brimonidine

Useful as adjunctive therapy but may cause:

• Allergy
• Fatigue
• Dry mouth

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Rho Kinase Inhibitors

Modern options include:

• Netarsudil

They may provide additional IOP lowering, particularly when target pressure is not reached with other therapies.

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Oral Carbonic Anhydrase Inhibitors

Examples include:

• Acetazolamide
• Methazolamide

These are not routinely used long term for uncomplicated OHT because of systemic adverse effects.

They may be used temporarily in selected cases with very high IOP.

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Surgery

Incisional glaucoma surgery is rarely required for isolated ocular hypertension.

Procedures such as:

• Trabeculectomy
• Tube shunt

are generally reserved for patients who:

• Develop definite glaucoma
• Have extremely high uncontrolled IOP
• Fail medical and laser treatment

⸻

MIGS

Minimally invasive glaucoma surgery is generally not performed solely for uncomplicated OHT unless:

• Cataract surgery is being performed
• There is another compelling indication

Treatment burden should be proportional to disease risk.

⸻

Follow-Up

Follow-up frequency should be individualized according to:

• IOP
• CCT
• Optic nerve appearance
• OCT findings
• Visual field findings
• Risk of conversion

⸻

High-Risk OHT

Patients at higher risk may be followed approximately every:

3–6 months

with periodic:

• IOP measurements
• Optic nerve examination
• OCT
• Visual field testing

⸻

Low-Risk Stable OHT

Once stability is established, lower-risk patients may often be followed every:

6–12 months

depending on individual circumstances.

⸻

Patient Monitoring

Monitor for the first evidence of conversion to glaucoma:

• Progressive cup enlargement
• Neuroretinal rim thinning
• RNFL loss
• Ganglion cell loss
• Reproducible glaucomatous field defect
• Disc hemorrhage

⸻

Risk Calculators

OHTS/EGPS-based risk calculators can estimate the approximate risk of developing glaucoma using factors such as:

• Age
• IOP
• CCT
• Vertical cup-to-disc ratio
• Visual field PSD

They can help guide treatment decisions but should not replace clinical judgment.

⸻

Patient Education

Patients should understand that:

• Ocular hypertension is not the same as glaucoma.
• Many patients never develop optic nerve damage.
• Elevated IOP increases future glaucoma risk.
• Regular monitoring is necessary even when vision is normal.
• Treatment can reduce the risk of developing glaucoma.

⸻

Medication Adherence

For patients receiving drops:

• Use medications consistently.
• Learn proper instillation.
• Consider punctal occlusion to reduce systemic absorption.
• Report ocular allergy or systemic adverse effects.

Poor adherence may make apparent treatment failure difficult to interpret.

⸻

Prognosis

The overall prognosis is excellent when patients are appropriately monitored.

Most patients with OHT do not rapidly develop glaucoma.

Risk varies greatly between individuals.

⸻

OHTS Prognosis

At approximately 5 years:

• About 9.5% of untreated participants developed primary open-angle glaucoma.
• About 4.4% of treated participants developed glaucoma.

Thus, most patients remained free of glaucoma during that period even without treatment.

This supports a risk-based rather than automatic treatment approach.

⸻

Complications

The principal complication is:

Conversion to primary open-angle glaucoma

with subsequent:

• RNFL loss
• Optic nerve damage
• Visual field loss
• Permanent visual impairment if uncontrolled

Treatment-related complications may include:

• Ocular surface disease
• Medication allergy
• Systemic drug effects
• Laser-related inflammation or transient IOP spike

⸻

Ophthalmology Pearls

• Ocular hypertension = elevated IOP without glaucomatous optic nerve, RNFL, or visual field damage.
• An IOP above 21 mmHg is a statistical threshold, not a biologic definition of glaucoma.
• OHT is a risk state, not established optic neuropathy.
• The major OHTS predictors of conversion are older age, higher IOP, larger vertical cup-to-disc ratio, higher visual field PSD, and thinner CCT.
• Thin corneas increase risk and may cause IOP underestimation; thick corneas may cause higher measured IOP.
• Do not use a simplistic numerical formula to “correct” IOP for corneal thickness.
• Gonioscopy, pachymetry, OCT, optic nerve examination, and visual fields are fundamental to diagnosis.
• Not every patient with ocular hypertension needs treatment.
• OHTS showed that treatment reduced 5-year conversion from approximately 9.5% to 4.4%.
• A useful initial treatment concept is roughly 20% IOP reduction, adjusted according to the patient’s risk.
• SLT or a prostaglandin analog are appropriate first-line options in many patients when treatment is indicated.
• Incisional glaucoma surgery is rarely appropriate for uncomplicated OHT.
• Long-term management should be based on risk of conversion and evidence of structural or functional progression.

Ophthalmology – Ocular Adnexal Lymphoma (OAL)

Basics

Description

Ocular adnexal lymphoma (OAL) is a lymphoid malignancy involving structures surrounding the globe, including the:

• Conjunctiva
• Eyelids
• Orbit
• Lacrimal gland
• Lacrimal drainage apparatus

Most OALs are:

• B-cell lymphomas
• Non-Hodgkin lymphomas

Ocular adnexal lymphoid proliferations range from:

• Reactive lymphoid hyperplasia
• Clonal lymphoproliferative disease
• Overt lymphoma

These entities cannot reliably be distinguished clinically and usually require tissue biopsy.

Important Distinction

Ocular adnexal lymphoma is different from:

Primary vitreoretinal lymphoma

Primary vitreoretinal lymphoma is usually considered part of the primary central nervous system lymphoma spectrum and involves the:

• Retina
• Vitreous
• Optic nerve in some cases

OAL, by contrast, primarily involves the ocular adnexa.

Major Histologic Subtypes

The most common ocular adnexal lymphomas include:

Indolent Lymphomas

• Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma)
• Follicular lymphoma
• Small lymphocytic lymphoma/chronic lymphocytic leukemia

More Aggressive Lymphomas

• Diffuse large B-cell lymphoma (DLBCL)
• Mantle cell lymphoma

The most common subtype is:

Extranodal marginal zone/MALT lymphoma

which accounts for approximately half or more of many OAL series.

Epidemiology

OAL predominantly affects:

• Middle-aged and older adults

The typical age at presentation is approximately:

60–70 years

It is uncommon in children.

There is no strong consistent sex predilection overall, although epidemiology varies among lymphoma subtypes.

OAL represents an important proportion of adult orbital malignancies.

Risk Factors

Potential risk factors include:

• Chronic immune stimulation
• Autoimmune disease
• Immunosuppression
• HIV infection
• Previous organ transplantation
• Long-term immunosuppressive therapy

Autoimmune diseases associated with increased lymphoma risk include:

• Sjögren syndrome
• Rheumatoid arthritis
• Other chronic autoimmune disorders

Genetics

There is no single inherited genetic predisposition responsible for most OAL.

Individual lymphoma subtypes may have characteristic molecular abnormalities.

Examples include alterations involving pathways of:

• NF-κB signaling
• B-cell proliferation
• Apoptosis

Molecular and cytogenetic testing may help classify difficult cases.

Pathophysiology

OAL results from clonal proliferation of lymphocytes, usually mature B cells.

The biological behavior depends heavily on the cell of origin.

For example:

• MALT lymphoma usually behaves indolently
• DLBCL is aggressive
• Mantle cell lymphoma has a strong tendency toward systemic dissemination

Chronic Immune Stimulation

Long-standing immune stimulation may contribute to development of some lymphomas.

This concept is well established in disorders such as:

• Helicobacter pylori-associated gastric MALT lymphoma

A possible association between ocular adnexal MALT lymphoma and Chlamydia psittaci has been reported in some geographic regions, but results have been inconsistent.

Therefore:

Routine antibiotic therapy is not considered standard treatment for all OAL.

Commonly Associated Conditions

Most patients have no obvious predisposing disease.

Possible associations include:

• HIV infection
• Sjögren syndrome
• Rheumatoid arthritis
• Chronic immunosuppression
• Other systemic lymphomas

Clinical Presentation

OAL typically presents with:

• Slowly progressive
• Painless
• Nonspecific

ocular or orbital symptoms.

Common complaints include:

• Eyelid swelling
• Conjunctival mass
• Proptosis
• Ptosis
• Orbital fullness
• Lacrimal gland enlargement

Diplopia and visual loss are less common.

Pain

Most indolent OAL is painless.

Pain may raise concern for:

• Aggressive lymphoma
• Rapid tumor growth
• Inflammation
• Bone involvement
• Alternative diagnosis

Conjunctival Lymphoma

The classic conjunctival appearance is a:

“Salmon-patch” lesion

This is usually:

• Pink
• Fleshy
• Smooth
• Subconjunctival
• Flat or mildly elevated

Common locations include:

• Fornix
• Bulbar conjunctiva
• Tarsal conjunctiva

Eyelid and Orbital Disease

Possible findings include:

• Painless eyelid thickening
• Palpable nodules
• Ptosis
• Proptosis
• Globe displacement
• Lacrimal gland enlargement

The lesion often molds around normal orbital structures rather than destroying them.

Lacrimal Gland Disease

Lacrimal gland lymphoma may present with:

• Superotemporal orbital fullness
• Ptosis
• Inferomedial globe displacement
• Painless gland enlargement

Lacrimal gland involvement may be associated with a greater likelihood of systemic disease than isolated conjunctival involvement.

Examination

A complete ocular examination should include:

• Visual acuity
• Pupillary responses
• Color vision when indicated
• Motility
• Globe position
• Slit-lamp examination
• Eyelid eversion
• Palpation of orbit and lacrimal gland
• Dilated fundus examination

Eyelid Eversion

Always evert the eyelids and inspect:

• Superior fornix
• Inferior fornix
• Tarsal conjunctiva

Subtle conjunctival lymphoma may otherwise be missed.

Vision and Pupils

Visual acuity and pupillary responses are often normal.

An optic neuropathy is unusual in indolent disease.

Features concerning for more advanced or aggressive disease include:

• Reduced vision
• Dyschromatopsia
• RAPD
• Optic disc edema
• Compressive optic neuropathy

Proptosis and Motility

OAL may cause:

• Mild proptosis
• Globe displacement

However, severe ophthalmoplegia or painful restrictive motility is less typical of indolent lymphoma and should raise consideration of:

• Aggressive lymphoma
• Idiopathic orbital inflammation
• Invasive infection
• Metastatic disease

Diagnosis

Definitive diagnosis requires:

Tissue biopsy

Clinical appearance alone cannot reliably distinguish:

• Reactive lymphoid hyperplasia
• MALT lymphoma
• Follicular lymphoma
• Other lymphoma subtypes

Biopsy

The goal of surgery is generally:

Adequate diagnostic tissue acquisition

rather than complete tumor excision.

Complete excision may be unnecessary and can increase morbidity.

Proper Tissue Handling

This is critical.

The specimen may need to be divided for:

• Histopathology
• Immunohistochemistry
• Flow cytometry
• Molecular studies
• Cytogenetic testing

Fresh, unfixed tissue is required for:

Flow cytometry

Therefore, coordination with pathology before biopsy is highly advisable.

Histopathology

Evaluation may establish:

• Cell lineage
• Monoclonality
• Lymphoma subtype
• Grade
• Proliferative activity

Markers vary according to subtype.

For B-cell lymphomas, immunophenotyping often includes markers such as:

• CD20
• CD79a
• PAX5

Additional markers help distinguish:

• MALT lymphoma
• Follicular lymphoma
• Mantle cell lymphoma
• DLBCL
• CLL/SLL

Reactive Lymphoid Hyperplasia

Reactive lymphoid hyperplasia is generally a:

• Polyclonal
• Benign or reactive lymphoid proliferation

However, clinically it may resemble lymphoma.

Long-term observation may be appropriate because persistent or recurrent lymphoid lesions occasionally precede or coexist with lymphoma.

Imaging

Orbital CT or MRI

Imaging is usually obtained for suspected OAL.

It helps determine:

• Extent of orbital involvement
• Lacrimal gland involvement
• Extraocular muscle involvement
• Bone changes
• Sinus extension
• Bilaterality

Typical Imaging Appearance

OAL often appears as:

• Homogeneous soft-tissue mass
• Well-defined lesion
• Infiltrative lesion molding around orbital structures

Characteristic behavior includes:

Molding to orbital anatomy without marked bone destruction

Bone Erosion

Bone erosion is uncommon in typical indolent OAL.

Its presence should raise concern for:

• Aggressive lymphoma
• Metastatic tumor
• Lacrimal gland epithelial malignancy
• Invasive infection

Conjunctival Disease and Orbital Imaging

Even apparently localized conjunctival lymphoma may have deeper orbital extension.

Therefore, orbital imaging should be considered as part of initial assessment.

Systemic Staging

After histologic confirmation, systemic staging is essential.

Evaluation commonly includes:

• Hematology/oncology consultation
• CBC with differential
• Renal function
• Liver function
• LDH
• Additional lymphoma-specific laboratory studies

PET/CT

FDG PET/CT is frequently used for staging many lymphoma subtypes.

It can identify:

• Nodal disease
• Extranodal disease
• Distant systemic involvement
• Treatment response

Its sensitivity varies according to lymphoma histology.

Bone Marrow Biopsy

Bone marrow examination may be considered depending on:

• Lymphoma subtype
• Stage
• PET/CT findings
• Blood counts
• Oncologist preference

It is no longer automatically required for every patient with every lymphoma subtype.

CNS Evaluation

Lumbar puncture or CNS evaluation is reserved for selected high-risk situations.

It is not routine for typical localized indolent OAL.

Differential Diagnosis

Important differential diagnoses include:

• Reactive lymphoid hyperplasia
• Idiopathic orbital inflammatory disease
• Sarcoidosis
• Granulomatosis with polyangiitis
• Metastatic carcinoma
• Lacrimal gland pleomorphic adenoma
• Adenoid cystic carcinoma
• Conjunctival neoplasia
• Orbital metastasis
• IgG4-related disease
• Sino-orbital fungal infection

IgG4-Related Disease

IgG4-related ophthalmic disease can closely mimic lymphoma.

It may involve:

• Lacrimal glands
• Extraocular muscles
• Infraorbital nerves
• Orbit

Histopathologic evaluation is essential because IgG4-related disease and lymphoma may occasionally coexist.

Treatment Principles

Treatment depends on:

• Histologic subtype
• Grade
• Stage
• Location
• Laterality
• Patient age
• Comorbidities

There is no single treatment appropriate for all OAL.

Localized Indolent OAL

For localized MALT or low-grade lymphoma, treatment commonly includes:

External-beam radiation therapy

This provides excellent local control.

Radiation Therapy

Conventional definitive radiation doses for localized indolent OAL are often approximately:

20–30 Gy

depending on:

• Histology
• Treatment protocol
• Anatomic site

Lower-dose regimens may be considered in selected cases.

Ultra-Low-Dose Radiation

Very low-dose radiation, such as:

4 Gy in 2 fractions

has been used for selected indolent ocular adnexal lymphomas.

Advantages include:

• Reduced treatment burden
• Lower radiation toxicity

However, local control may be less durable than with conventional definitive dosing in some patients.

An adaptive approach may be used in selected centers.

Radiation Complications

Potential ocular complications include:

• Dry eye
• Keratitis
• Cataract
• Retinopathy
• Optic neuropathy
• Lacrimal gland dysfunction

Risk depends on:

• Total dose
• Radiation field
• Ocular shielding
• Location of tumor

Rituximab

Rituximab targets CD20-positive B cells.

It may be used:

• Systemically
• As part of combination chemotherapy
• In selected recurrent or disseminated indolent B-cell lymphomas

Responses can be excellent, although recurrence may occur.

Systemic Chemotherapy

Systemic therapy is generally indicated for:

• Disseminated lymphoma
• Aggressive histologic subtype
• Certain bilateral or multifocal presentations
• Relapsed disease

Treatment is dictated by lymphoma subtype.

Diffuse Large B-Cell Lymphoma

DLBCL requires systemic oncologic treatment.

A common approach includes:

Rituximab-based multiagent chemotherapy, often an R-CHOP-type regimen when appropriate.

Radiation may also be added in selected cases.

Mantle Cell Lymphoma

Mantle cell lymphoma is commonly associated with:

• Bilateral ocular involvement
• Systemic disease
• More aggressive clinical behavior

It usually requires systemic hematologic treatment rather than local therapy alone.

Follicular Lymphoma

Management depends on:

• Stage
• Grade
• Symptoms

Localized disease may be treated with radiation.

Systemic disease may require:

• Observation in selected low-burden cases
• Rituximab
• Systemic immunochemotherapy

Observation

Observation may be appropriate in selected patients with:

• Completely excised very small indolent lesions
• Significant comorbidity
• Very low disease burden
• No systemic involvement

However, careful systemic staging and long-term surveillance remain necessary.

Antibiotic Therapy

Antibiotics have been investigated because of the proposed association between some MALT lymphomas and infectious organisms.

However:

Routine empiric antibiotic treatment is not standard for OAL.

Any such treatment should be based on:

• Geographic evidence
• Demonstrated infection
• Specialist recommendations

Role of Surgery

Surgery is mainly used for:

Diagnosis

rather than definitive tumor removal.

Extensive orbital excision is generally avoided because:

• Lymphoma is radiosensitive
• Lymphoma is chemosensitive
• Complete excision may cause unnecessary morbidity

Referral

All confirmed OAL should generally be managed with:

• Ophthalmology/oculoplastic surgery
• Hematology-oncology

Additional involvement may include:

• Radiation oncology
• Pathology
• Medical oncology

Prognostic Factors

Prognosis depends predominantly on:

• Histologic subtype
• Systemic stage
• Response to treatment

Generally favorable features include:

• Localized disease
• Unilateral conjunctival involvement
• MALT histology

Less favorable features include:

• Aggressive histology
• Bilateral disease
• Eyelid involvement
• Lacrimal gland involvement
• Bone destruction
• Optic neuropathy
• Systemic dissemination

Follow-Up

Long-term surveillance is essential because OAL may:

• Recur locally
• Appear in the fellow orbit
• Develop at distant extranodal sites
• Become associated with systemic lymphoma

Follow-up often continues for:

Years to decades

Ocular Monitoring

Initially, patients may be examined every few weeks or months during therapy.

Later surveillance evaluates:

• Conjunctiva
• Eyelids
• Orbit
• Lacrimal gland
• Motility
• Vision
• Treatment complications

Once stable, follow-up intervals may extend to:

6–12 months

depending on subtype and oncologic guidance.

Systemic Monitoring

Systemic surveillance is coordinated by oncology and may include:

• Clinical examination
• Blood tests
• PET/CT or other imaging when indicated

The exact schedule depends on lymphoma subtype and stage.

Patient Education

Patients should understand that:

• OAL is not a single disease.
• Prognosis depends strongly on histologic subtype.
• Even localized disease requires systemic staging.
• Long-term follow-up remains necessary after successful treatment.
• Recurrence may occur years after initial therapy.

Prognosis

MALT / Extranodal Marginal Zone Lymphoma

Usually:

• Indolent
• Highly treatment-responsive
• Associated with excellent disease-specific survival

Local recurrence or systemic dissemination can nevertheless occur.

Follicular Lymphoma

Usually has an indolent course but may:

• Recur
• Become systemic
• Rarely transform to a more aggressive lymphoma

DLBCL

DLBCL is an aggressive malignancy requiring prompt systemic therapy.

Prognosis depends on:

• Stage
• Age
• Performance status
• Molecular characteristics
• Treatment response

Mantle Cell Lymphoma

Mantle cell lymphoma often has:

• Greater systemic involvement
• Higher recurrence risk
• More aggressive behavior

than MALT lymphoma.

Modern targeted therapies have substantially changed management compared with older historical series.

Complications

Local Disease Complications

Possible complications include:

• Recurrence
• Proptosis
• Diplopia
• Ptosis
• Optic nerve compression
• Visual loss

Treatment-Related Complications

Radiation may cause:

• Dry eye
• Cataract
• Keratitis
• Retinopathy
• Optic neuropathy

Systemic therapy may cause:

• Cytopenias
• Infection
• Organ toxicity
• Other regimen-specific complications

Disease-Related Complications

Potential long-term complications include:

• Systemic dissemination
• Relapse
• Transformation to a more aggressive lymphoma
• Treatment failure

Ophthalmology Pearls

• Ocular adnexal lymphoma involves the conjunctiva, eyelids, orbit, lacrimal gland, or lacrimal drainage system.
• The most common subtype is extranodal marginal zone/MALT lymphoma.
• The classic conjunctival lesion is a painless salmon-patch mass.
• Always evert the eyelids to inspect the fornices and tarsal conjunctiva.
• OAL usually presents as a slow-growing, painless lesion; pain, bone destruction, or optic neuropathy should raise concern for more aggressive disease.
• OAL often molds around orbital structures rather than destroying them.
• Clinical examination cannot reliably distinguish reactive lymphoid hyperplasia from lymphoma—biopsy is required.
• Correct specimen handling is critical: fresh tissue is needed for flow cytometry, while formalin-fixed tissue is used for routine histology and immunohistochemistry.
• Surgery is primarily diagnostic, not an attempt at wide complete excision.
• Every confirmed OAL requires systemic staging and hematology-oncology involvement.
• Localized indolent OAL is highly responsive to radiation therapy.
• Aggressive subtypes such as DLBCL and mantle cell lymphoma generally require systemic therapy.
• OAL is distinct from primary vitreoretinal lymphoma, which belongs to the CNS lymphoma spectrum.
• Even after successful local treatment, long-term systemic and ophthalmic surveillance is mandatory.

Ophthalmology – Occipital Lobe Disorders

Basics

Description

Occipital lobe disorders are conditions affecting the posterior cerebral cortex, which is primarily responsible for processing visual information.

Because the occipital lobes contain the primary visual cortex and adjacent visual association areas, lesions can produce:

• Homonymous visual field defects
• Cortical blindness
• Visual hallucinations
• Color perception abnormalities
• Visual agnosias
• Reading difficulty
• Visual illusions
• Palinopsia
• Higher-order visual processing deficits

The exact deficit depends on:

• Side of involvement
• Size of the lesion
• Whether one or both occipital lobes are affected
• Whether adjacent parietal, temporal, or splenial regions are involved

⸻

Epidemiology

Epidemiology depends entirely on the underlying cause.

Occipital dysfunction may occur from:

• Stroke
• Trauma
• Hemorrhage
• Tumor
• Migraine
• Seizure
• Infection
• Demyelination
• Neurodegenerative disease

⸻

Etiology

Common Causes

Important causes include:

• Ischemic stroke
• Intracranial hemorrhage
• Traumatic brain injury
• Brain tumor
• Infection
• Migraine with visual aura
• Seizure

⸻

Less Common Causes

Other causes include:

• Demyelinating disease
• Posterior reversible encephalopathy syndrome (PRES)
• MELAS
• Posterior cortical atrophy
• Creutzfeldt–Jakob disease
• Progressive multifocal leukoencephalopathy
• Hypoxic-ischemic injury
• Severe hypotension
• Vasculitis
• Toxic-metabolic injury

⸻

Vascular Anatomy

The occipital lobes are supplied predominantly by the:

Posterior cerebral arteries

Lesions involving the posterior cerebral artery territory are therefore a classic cause of:

• Contralateral homonymous hemianopia
• Occipital visual loss
• Visual association deficits

⸻

Pathophysiology

Visual information travels from:

• Retina
• Optic nerve
• Optic chiasm
• Optic tract
• Lateral geniculate nucleus
• Optic radiations
• Primary visual cortex in the occipital lobe

A lesion posterior to the optic chiasm produces a:

Contralateral homonymous visual field defect

The more posterior the lesion, the more likely the defect is to be:

• Congruous
• Sharply demarcated
• Associated with preserved pupillary reactions

⸻

Diagnosis

History

Patients may report:

• Blurred vision on one side
• Missing half of the visual field
• Bumping into objects
• Difficulty reading
• Difficulty locating objects
• Difficulty recognizing objects
• Difficulty recognizing colors
• Visual hallucinations
• Visual distortions
• Recurrent visual phenomena

Patients may mistakenly believe that the problem is in one eye when the defect actually affects the same half of the visual field in both eyes.

⸻

Visual Field Symptoms

Typical complaints include:

• “I cannot see things on my left/right side.”
• “I keep bumping into doorframes.”
• “I lose my place when reading.”
• “Objects disappear on one side.”

Some unilateral occipital lesions are initially asymptomatic and discovered only during formal visual field testing.

⸻

Homonymous Hemianopia

The classic finding is:

Loss of the same half of the visual field in both eyes

For example:

• Right occipital lesion → left homonymous hemianopia
• Left occipital lesion → right homonymous hemianopia

⸻

Congruity

Occipital lesions often produce highly:

Congruous

visual field defects.

This means the defects in both eyes closely resemble each other in:

• Shape
• Size
• Location

More anterior retrochiasmal lesions may produce less congruous defects.

⸻

Macular Sparing

Some occipital lesions produce:

Macular sparing

in which central vision is preserved despite a homonymous hemianopia.

Possible explanations include:

• Dual blood supply to the occipital pole
• Incomplete infarction of the macular cortex
• Variable cortical representation

Macular sparing is suggestive of occipital disease but is not mandatory.

⸻

Occipital Tip Lesions

Small lesions at the occipital pole may cause:

Congruous homonymous central scotomas

because the posterior occipital cortex contains a disproportionately large representation of central vision.

⸻

Homonymous Quadrantanopia

Occipital lesions may also produce:

• Superior homonymous quadrantanopia
• Inferior homonymous quadrantanopia

depending on which portion of the visual cortex is involved.

⸻

Temporal Crescent Defect

The extreme temporal peripheral field between approximately:

60–90 degrees

is represented in the most anterior portion of the contralateral visual cortex.

A very anterior occipital lesion may rarely produce an isolated:

Contralateral monocular temporal crescent defect

This is sometimes called the temporal crescent syndrome.

⸻

Bilateral Occipital Lesions

Bilateral occipital damage may cause:

• Bilateral homonymous field defects
• Severe visual impairment
• Cortical blindness

⸻

Cortical Blindness

Cortical blindness is profound visual loss caused by bilateral occipital cortical dysfunction despite structurally normal eyes and anterior visual pathways.

Typical findings include:

• Severe or complete visual loss
• Normal ocular examination
• Normal optic discs initially
• Preserved pupillary light responses
• No blink to visual threat
• No meaningful visual response

⸻

Common Causes of Cortical Blindness

Important causes include:

• Bilateral posterior cerebral artery infarction
• Severe hypoxic-ischemic injury
• Prolonged hypotension
• PRES
• Encephalitis
• Toxic-metabolic injury

⸻

Pupillary Findings

Because the afferent pupillary pathway branches before reaching the visual cortex:

Pupillary reactions are usually normal in isolated occipital cortical blindness.

This is an important localization clue.

⸻

Anton Syndrome

Anton syndrome refers to:

• Cortical blindness
• Lack of awareness or denial of blindness

Patients may:

• Insist that they can see
• Confabulate visual descriptions
• Attempt to navigate despite profound visual loss

It usually reflects broader cortical dysfunction beyond isolated primary visual cortex damage.

⸻

Visual Hallucinations

Occipital disorders may produce:

• Simple hallucinations
• Complex hallucinations

⸻

Simple Visual Hallucinations

Examples include:

• Flashes
• Phosphenes
• Photopsias
• Colored lights
• Geometric shapes

These may occur with:

• Occipital seizures
• Migraine
• Structural lesions

⸻

Formed Visual Hallucinations

More complex hallucinations may include:

• People
• Animals
• Objects
• Scenes

Complex formed hallucinations often suggest involvement extending beyond primary visual cortex into visual association areas.

⸻

Visual Illusions

Patients may misperceive real objects.

Examples include:

• Distortion of shape
• Distortion of size
• Distortion of position
• Movement of stationary objects

⸻

Palinopsia

Palinopsia is persistence or recurrence of a visual image after the stimulus has disappeared.

It may occur with:

• Occipital or posterior cortical lesions
• Seizures
• Migraine
• Certain medications
• Toxic states

⸻

Polyopia

Cerebral polyopia refers to seeing multiple images of a single object from a cortical disorder.

It should be distinguished from:

• Ocular monocular diplopia
• Binocular diplopia from ocular misalignment

⸻

Dyschromatopsia

Occipital lesions may cause:

• Generalized dyschromatopsia
• Hemiachromatopsia
• Cerebral achromatopsia

⸻

Cerebral Achromatopsia

Bilateral lesions involving color-processing regions, particularly ventral occipitotemporal cortex, can produce severe impairment of color perception despite normal retinal color mechanisms.

⸻

Hemiachromatopsia

A unilateral lesion may cause impaired color perception limited to:

One hemifield

while the rest of vision remains relatively preserved.

⸻

Color Agnosia

Patients may perceive colors but be unable to:

• Name them
• Associate them correctly with objects

This represents a higher cortical processing deficit rather than a primary color vision defect.

⸻

Visual Agnosia

Visual agnosia is inability to recognize an object despite adequate visual acuity and basic perception.

Patients may be able to:

• Describe an object’s shape
• Trace its outline

yet fail to identify it visually.

Recognition through touch or sound may remain intact.

⸻

Prosopagnosia

Bilateral or right-dominant occipitotemporal lesions can cause:

Prosopagnosia

or inability to recognize familiar faces.

⸻

Alexia

A dominant posterior cerebral hemisphere lesion may cause:

• Alexia
• Reading difficulty
• Visual language disturbance

⸻

Alexia Without Agraphia

A classic syndrome from a dominant occipital lesion plus involvement of the splenium of the corpus callosum is:

Alexia without agraphia

The patient:

• Cannot read
• Can still write

This results from disruption of visual information reaching the dominant language cortex.

⸻

Riddoch Phenomenon

Riddoch phenomenon refers to the ability to perceive:

Moving objects better than stationary objects

within an otherwise blind visual field.

It may occur with damaged primary visual cortex but partially preserved extrastriate motion pathways.

⸻

Blindsight

Some patients with cortical visual loss can respond to visual stimuli without conscious visual awareness.

This phenomenon is called:

Blindsight

It likely reflects residual visual processing through alternative pathways.

⸻

Optic Atrophy After Early Occipital Injury

If severe occipital or retrochiasmal injury occurs early in life, retrograde transsynaptic degeneration may eventually cause:

• RNFL thinning
• Optic disc pallor

This may complicate localization years later.

⸻

Examination

A complete neuro-ophthalmic examination should include:

• Best-corrected visual acuity
• Pupils
• Color vision
• Ocular motility
• Visual fields
• Fundus examination
• Neurologic examination

⸻

Visual Field Testing

Formal perimetry is essential.

Useful techniques include:

• Automated static perimetry
• Goldmann kinetic perimetry
• Confrontation fields in acute or severely impaired patients

⸻

Key Localizing Field Patterns

Occipital disease may produce:

• Congruous homonymous hemianopia
• Homonymous quadrantanopia
• Homonymous central scotoma
• Temporal crescent defect
• Bilateral cortical field loss

⸻

Neurologic Examination

Look for associated:

• Aphasia
• Memory impairment
• Neglect
• Sensory deficits
• Weakness
• Ataxia
• Seizures
• Cognitive dysfunction

These may help localize involvement beyond the occipital lobe.

⸻

Imaging

Acute Presentation

If symptoms are acute, neuroimaging is urgent.

Initial evaluation may include:

• Noncontrast CT to exclude intracranial hemorrhage
• CT angiography when vascular occlusion is suspected
• MRI with diffusion-weighted imaging for ischemic stroke

⸻

MRI

MRI is generally the preferred imaging modality for nonemergent or diagnostically uncertain occipital disease.

Useful sequences include:

• Diffusion-weighted imaging
• FLAIR
• T1
• T2
• Contrast-enhanced imaging when indicated

⸻

Functional Imaging

In selected disorders where conventional imaging is unrevealing, functional imaging may demonstrate abnormal posterior cortical activity.

Options include:

• FDG-PET
• SPECT
• Functional MRI

These may be particularly useful in:

• Neurodegenerative disease
• Posterior cortical atrophy
• Selected seizure disorders

⸻

Posterior Reversible Encephalopathy Syndrome

PRES often involves the parieto-occipital regions.

Typical features include:

• Headache
• Seizures
• Altered mental status
• Visual disturbance
• Cortical blindness

Common associations include:

• Severe hypertension
• Eclampsia
• Renal failure
• Cytotoxic or immunosuppressive drugs

MRI typically demonstrates vasogenic edema in posterior cerebral white matter and cortex.

⸻

Migraine

Migraine aura may produce:

• Scintillating scotoma
• Zigzag lines
• Expanding fortification spectra
• Homonymous visual loss

Typical migraine aura:

• Evolves gradually
• Spreads over minutes
• Usually resolves within an hour

Sudden fixed visual field loss should not automatically be attributed to migraine.

⸻

Occipital Seizures

Occipital seizures may produce:

• Brief recurrent flashes
• Colored circles
• Simple geometric hallucinations
• Transient visual loss

They are generally:

• Sudden
• Brief
• Stereotyped

EEG may be useful.

⸻

Posterior Cortical Atrophy

Posterior cortical atrophy is a neurodegenerative syndrome characterized by progressive impairment of higher-order visual processing.

Patients may develop:

• Difficulty reading
• Difficulty recognizing objects
• Difficulty judging spatial relationships
• Simultanagnosia
• Visual agnosia

Alzheimer pathology is a common underlying cause.

⸻

Heidenhain Variant of Creutzfeldt-Jakob Disease

This rare form of prion disease may begin with prominent visual symptoms such as:

• Visual field loss
• Visual distortions
• Visual agnosia

Rapid neurologic decline follows.

⸻

MELAS

MELAS may produce posterior cortical stroke-like episodes with:

• Visual field defects
• Cortical blindness
• Seizures
• Headache

Lesions often do not conform strictly to vascular territories.

⸻

Differential Diagnosis

Important alternatives include lesions of:

• Optic tract
• Lateral geniculate nucleus
• Temporal optic radiations
• Parietal optic radiations

These can also produce homonymous visual field defects.

⸻

Optic Tract Lesions

May produce:

• Incongruous homonymous hemianopia
• RAPD in the eye with greater temporal field loss
• Optic atrophy over time

⸻

Temporal Lobe Lesions

May cause:

Contralateral superior homonymous quadrantanopia

from involvement of Meyer’s loop.

Associated findings may include:

• Memory disturbance
• Seizures
• Language abnormalities

⸻

Parietal Lobe Lesions

May cause:

Contralateral inferior homonymous quadrantanopia

and may be associated with:

• Sensory loss
• Neglect
• Higher cortical deficits

⸻

Functional Visual Loss

Cortical blindness may occasionally be mistaken for functional vision loss because:

• Eye examination is normal
• Pupils are reactive

However, objective visual field abnormalities, imaging, and neurologic findings establish the organic diagnosis.

⸻

Treatment

Treatment depends entirely on the underlying cause.

⸻

Acute Ischemic Stroke

Acute occipital infarction should be managed according to modern stroke protocols.

Potential treatments include:

• IV thrombolysis in eligible patients within the appropriate time window
• Mechanical thrombectomy in selected patients with treatable large-vessel occlusion
• Antiplatelet therapy
• Vascular risk-factor management

Treatment decisions should be made urgently through a stroke team.

⸻

Intracranial Hemorrhage

Management may include:

• Blood pressure control
• Reversal of anticoagulation
• Neurosurgical evaluation
• Intracranial pressure management

⸻

Tumors

Treatment may include:

• Surgical resection
• Radiation therapy
• Chemotherapy
• Targeted therapy

depending on tumor type.

⸻

Infection

Treat the specific organism.

Examples include:

• Antiviral therapy
• Antibiotics
• Antifungal therapy

depending on cause.

⸻

PRES

Management focuses on:

• Controlled blood pressure reduction
• Treatment of seizures
• Removal or adjustment of causative medications
• Treatment of underlying systemic disease

Visual function often improves substantially when PRES is promptly treated.

⸻

Migraine

Migraine treatment includes:

• Acute therapy
• Preventive therapy when appropriate
• Trigger management

New persistent field defects should not be assumed to be migraine without excluding stroke or other structural disease.

⸻

Seizures

Occipital epilepsy may require:

• Antiseizure medication
• Neurology follow-up

⸻

Visual Rehabilitation

Persistent homonymous visual field defects may benefit from rehabilitation.

Approaches include:

• Occupational therapy
• Saccadic scanning training
• Reading strategies
• Environmental modification
• Prism treatment

⸻

Saccadic Training

Patients can be trained to make larger eye movements toward the blind hemifield.

Potential benefits include:

• Better obstacle detection
• Improved reading
• Improved environmental scanning

This does not restore the missing visual cortex but improves compensation.

⸻

Prism Therapy

Prisms can shift information from the blind hemifield into the seeing field.

Peripheral prism systems may help selected patients with:

• Homonymous hemianopia

Success varies and adaptation is required.

⸻

Reading Rehabilitation

Reading difficulties may improve with:

• Structured scanning strategies
• Line guides
• Increased text spacing
• Electronic magnification
• Direction-specific reading training

⸻

Driving

Driving eligibility depends on:

• Extent of field loss
• Local legal requirements
• Functional adaptation

Patients with homonymous hemianopia often fail minimum legal field standards.

Driving advice should follow local regulations.

⸻

Admission

Hospital admission is generally required for:

• Acute stroke
• Intracranial hemorrhage
• Significant mass effect
• Encephalitis
• Severe PRES
• Acute neurologic deterioration

⸻

Follow-Up

Follow-up depends on the cause.

Monitoring may involve:

• Neuro-ophthalmology
• Neurology
• Stroke medicine
• Neurosurgery
• Oncology
• Rehabilitation services

Repeat visual field testing helps document:

• Recovery
• Stability
• Progression

⸻

Prognosis

Prognosis varies widely.

Factors include:

• Etiology
• Size of lesion
• Unilateral vs bilateral disease
• Age
• Degree of cortical injury
• Speed of treatment

Some recovery may occur after stroke, particularly in the first several months.

Persistent dense field defects may remain permanent.

⸻

Ophthalmology Pearls

• Occipital lesions produce contralateral homonymous visual field defects.
• The more posterior the lesion, the more congruous the defect tends to be.
• Macular sparing suggests occipital involvement but is not obligatory.
• Small occipital pole lesions may cause homonymous central scotomas.
• Bilateral occipital injury can produce cortical blindness with normal pupils and normal ocular examination.
• Anton syndrome = cortical blindness with denial of blindness.
• A dominant occipital lesion plus splenial involvement may cause alexia without agraphia.
• Riddoch phenomenon means motion is perceived better than stationary objects.
• Simple visual hallucinations suggest occipital cortex irritation, especially migraine or seizure.
• Homonymous field loss should never be attributed to ocular disease alone without considering a retrochiasmal lesion.
• Acute homonymous visual field loss should be treated as a possible stroke emergency until proven otherwise.
• Persistent hemianopia may improve functionally with saccadic training, occupational therapy, and prisms, even when the visual field defect itself remains.

Ophthalmology – Congenital / Infantile Nystagmus

Basics

Description

Infantile nystagmus is an involuntary, rhythmic oscillation of the eyes beginning in early infancy, usually within the first 6 months of life.

The preferred modern term is:

Infantile nystagmus syndrome (INS)

rather than “congenital nystagmus,” because the nystagmus is often not present at birth and becomes apparent several weeks later.

It may occur:

• As an isolated ocular motor disorder
• Secondary to reduced visual input
• In association with albinism
• With retinal or optic nerve disease
• With strabismus
• As part of a neurologic or genetic syndrome

Epidemiology

Infantile nystagmus is uncommon.

Idiopathic infantile nystagmus has historically been estimated at approximately:

1 in 2,500–3,000 individuals

The overall prevalence of nystagmus, including sensory and strabismus-associated forms, is higher.

Major Categories

Important causes of nystagmus beginning in infancy include:

• Infantile nystagmus syndrome
• Sensory-deficit nystagmus
• Fusion maldevelopment nystagmus syndrome
• Spasmus nutans
• Neurologic nystagmus
• Vestibular nystagmus
• Drug- or toxin-induced eye oscillations

Risk Factors and Associations

Associated conditions include:

• Poor vision from infancy
• Albinism
• Foveal hypoplasia
• Retinal dystrophy
• Congenital stationary night blindness
• Optic nerve hypoplasia
• Congenital cataract
• Corneal opacity
• Childhood glaucoma
• Strabismus
• Developmental delay
• Neurologic abnormalities
• Chromosomal or genetic syndromes
• Family history of nystagmus

Genetics

Infantile nystagmus may occur with several inheritance patterns.

The best-established isolated nystagmus gene is:

FRMD7

which causes an X-linked form of infantile nystagmus.

Other genetic causes may be associated with:

• Albinism
• Retinal dystrophies
• Congenital stationary night blindness
• Foveal hypoplasia
• Developmental syndromes

For example:

GPR143 mutations cause X-linked ocular albinism and may be associated with infantile nystagmus.

Genetic counseling should be considered when there is:

• Positive family history
• Albinism
• Retinal dystrophy
• Syndromic features
• Unexplained infantile nystagmus

Pathophysiology

Stable fixation depends on accurate interaction between:

• Visual sensory input
• Ocular motor calibration
• Fixation control systems
• Vestibular pathways

Infantile nystagmus may develop because of either:

• Primary instability of ocular motor control
• Poor visual input during early visual development

There is no single mechanism explaining all cases.

Sensory-Deficit Nystagmus

Severe reduction of vision early in life can prevent normal calibration of ocular motor control.

Possible causes include:

• Bilateral congenital cataract
• Corneal opacity
• Severe retinal dystrophy
• Albinism
• Foveal hypoplasia
• Optic nerve hypoplasia
• Congenital glaucoma

The worse the early visual deprivation, the greater the risk of nystagmus.

Infantile Nystagmus Syndrome

INS usually becomes noticeable between approximately:

6 weeks and 6 months of age

Typical characteristics include:

• Horizontal oscillation
• Usually conjugate
• May be pendular early and develop jerk waveforms later
• Intensity varies with gaze position
• Often decreases with convergence
• Usually increases with fixation effort or stress
• Often has a null point

Null Point

The null point is the gaze position in which nystagmus intensity is lowest and visual acuity is often best.

A patient may adopt an abnormal head posture to place the eyes in the null position.

Examples include:

• Face turn
• Chin elevation
• Chin depression
• Head tilt

Foveation

Visual acuity in infantile nystagmus depends less on movement amplitude alone and more on periods during which the eyes remain close to the target.

These relatively stable periods are called:

Foveation periods

Longer and more accurate foveation generally corresponds with better vision.

Oscillopsia

Patients with infantile nystagmus usually do not experience oscillopsia, because the developing brain adapts to the eye movements.

Oscillopsia developing later should raise concern for:

• New acquired nystagmus
• Change in the pre-existing nystagmus
• Neurologic disease

History

Important questions include:

• Age when nystagmus was first noticed
• Progression or change
• Family history
• Abnormal head posture
• Photophobia
• Night blindness
• Better vision in dim or bright conditions
• Developmental delay
• Neurologic symptoms
• Previous brain injury
• Medications or toxin exposure

Photophobia

Photophobia may suggest:

• Albinism
• Achromatopsia
• Cone dystrophy
• Foveal hypoplasia
• Other cone dysfunction disorders

Night Vision Symptoms

Poor night vision may suggest:

• Congenital stationary night blindness
• Rod-cone dystrophy

Better vision in dim illumination with severe photophobia may occur in:

• Achromatopsia
• Cone dysfunction

Physical Examination

A full examination should assess:

• Best-corrected visual acuity
• Cycloplegic refraction
• Pupils
• Ocular alignment
• Motility
• Anterior segment
• Optic nerve
• Retina
• Fovea

Also assess:

• Head position
• Developmental status
• Neurologic examination when indicated

Characterizing the Nystagmus

Document:

• Direction
• Amplitude
• Frequency
• Pendular versus jerk waveform
• Conjugacy
• Symmetry
• Effect of gaze
• Effect of convergence
• Effect of monocular occlusion
• Null position
• Associated head posture

Direction

Classic INS is usually:

Horizontal

even in vertical gaze.

Predominantly vertical or torsional infantile nystagmus is less typical and should raise concern for neurologic or structural disease.

Effect of Convergence

Many patients with INS have reduced nystagmus intensity during:

Convergence

This can improve near visual acuity.

Strabismus

Strabismus is common in children with nystagmus.

Possible associations include:

• Infantile esotropia
• Sensory strabismus
• Albinism
• Poor visual acuity

Fusion Maldevelopment Nystagmus Syndrome

Previously called:

• Latent nystagmus
• Manifest latent nystagmus

It is strongly associated with:

• Infantile strabismus
• Disrupted binocular development

Characteristics include:

• Jerk nystagmus
• Increased intensity when one eye is covered
• Fast phase toward the viewing eye
• Direction reverses when fixation switches between eyes

Spasmus Nutans

Spasmus nutans usually begins during the:

First year of life

The classic triad is:

• Nystagmus
• Head nodding
• Abnormal head posture

The nystagmus is often:

• Fine
• High frequency
• Low amplitude
• Asymmetric
• Sometimes apparently monocular

Natural History of Spasmus Nutans

Typical spasmus nutans is usually benign and often improves spontaneously during early childhood.

However, atypical cases require evaluation for structural disease.

When Spasmus Nutans Is Concerning

Consider MRI when there is:

• Truly monocular nystagmus
• Marked asymmetry
• Optic nerve abnormality
• Visual loss
• Developmental delay
• Neurologic signs
• Persistent or progressive course
• Atypical age of onset

Rare parasellar, optic pathway, or chiasmal lesions may mimic spasmus nutans.

Albinism

Nystagmus is common in:

• Oculocutaneous albinism
• Ocular albinism

Associated ocular findings include:

• Iris transillumination
• Foveal hypoplasia
• Reduced pigmentation
• Optic pathway misrouting
• Strabismus
• Photophobia

Visual Evoked Potentials in Albinism

Multichannel VEP testing may demonstrate:

Excessive crossing of optic nerve fibers at the chiasm

and can support the diagnosis of albinism in selected uncertain cases.

It is not required in every typical case.

Congenital Stationary Night Blindness

CSNB is an important cause of infantile nystagmus when the fundus appears relatively normal.

Patients may have:

• Night blindness
• Myopia
• Strabismus
• Infantile nystagmus

Diagnosis is often established with:

Electroretinography

Diagnostic Testing

Cycloplegic Refraction

This is essential because correcting refractive error may significantly improve visual function.

Common refractive abnormalities include:

• Astigmatism
• Myopia
• Hyperopia

Optical Coherence Tomography

OCT is extremely useful for detecting:

• Foveal hypoplasia
• Macular dystrophy
• Retinal structural abnormalities
• Optic nerve pathology

Handheld OCT may be useful in young children.

Electroretinography

ERG should be considered when:

• Vision is reduced without clear structural explanation
• Retinal dystrophy is suspected
• CSNB is suspected
• Cone dysfunction is suspected

Visual Evoked Potentials

VEP may be useful for:

• Suspected albinism
• Visual pathway dysfunction
• Selected infants who cannot provide behavioral visual responses

Eye Movement Recording

Video-oculography or formal eye movement recording can characterize:

• Waveform
• Foveation
• Null point
• Frequency
• Amplitude

It is most useful in complex diagnostic or surgical planning cases.

Neuroimaging

MRI is not routinely necessary for a neurologically normal child with typical horizontal infantile nystagmus and an identifiable ocular or genetic cause.

MRI should be considered for:

• Vertical nystagmus
• Torsional nystagmus
• Markedly asymmetric nystagmus
• New or changing nystagmus
• Optic nerve hypoplasia
• Neurologic abnormalities
• Developmental regression
• Seizures
• Abnormal head circumference
• See-saw nystagmus
• Opsoclonus
• Suspected intracranial lesion

Opsoclonus

Opsoclonus is not true nystagmus.

It consists of:

• Chaotic
• Multidirectional
• Back-to-back saccades

In a child, opsoclonus should raise concern for:

• Neuroblastoma
• Postinfectious or autoimmune encephalopathy

This requires urgent systemic and neurologic evaluation.

Differential Diagnosis

Important differential diagnoses include:

• Infantile nystagmus syndrome
• Sensory-deficit nystagmus
• Fusion maldevelopment nystagmus syndrome
• Spasmus nutans
• Albinism
• CSNB
• Retinal dystrophy
• Optic nerve hypoplasia
• Congenital cataract
• Congenital glaucoma
• Gaze-evoked nystagmus
• Vestibular nystagmus
• Brainstem or cerebellar disease
• Intracranial tumor
• Drug- or toxin-induced eye oscillation
• Opsoclonus

Treatment Principles

Treatment goals are to:

• Maximize visual acuity
• Correct refractive error
• Treat amblyopia
• Improve ocular alignment
• Reduce abnormal head posture
• Improve foveation
• Treat the underlying ocular disorder

The objective is generally not to eliminate all visible nystagmus.

Refractive Correction

Accurate refractive correction is one of the most important interventions.

Options include:

• Spectacles
• Contact lenses

Contact lenses may sometimes provide better vision because:

• They move with the eye
• They reduce optical aberrations during eye movement
• Some patients experience modest reduction of nystagmus intensity

Amblyopia Treatment

Amblyopia should be treated when present.

Treatment may include:

• Optical correction
• Patching
• Atropine penalization when appropriate

Treatment decisions should account for associated strabismus and visual potential.

Treatment of Underlying Disease

Correct treatable visual deprivation as early as possible.

Examples include:

• Congenital cataract surgery
• Glaucoma treatment
• Corneal rehabilitation
• Appropriate retinal treatment

Early intervention is especially important during the sensitive period of visual development.

Photophobia Management

Patients with albinism or cone dysfunction may benefit from:

• Tinted lenses
• Photochromic lenses
• Sunglasses

These improve comfort but do not directly cure nystagmus.

Prism Treatment

Prisms may be useful in selected patients.

To shift the eyes toward the null point

Prisms can reduce the abnormal head posture.

To stimulate convergence

Base-out prisms may reduce nystagmus in patients whose nystagmus dampens with convergence.

Patients must have sufficient fusional ability for this approach.

Medical Treatment

Medication is not routinely required for infantile nystagmus.

Drugs studied in selected older patients include:

• Gabapentin
• Memantine

Some studies suggest reduction in nystagmus intensity or improvement in visual function, but responses are variable.

Medication is generally reserved for selected symptomatic patients under specialist care.

Older therapies such as baclofen or 5-hydroxytryptophan have limited evidence.

Surgery

Surgery may be considered when there is:

• Significant abnormal head posture
• Stable eccentric null point
• Associated strabismus
• Functionally important nystagmus

Kestenbaum-Anderson Procedure

The Anderson-Kestenbaum procedure shifts the eyes so that the null point lies closer to primary gaze.

The major goal is:

Reduction of abnormal head posture

rather than complete elimination of nystagmus.

Large Rectus Recessions

Large recessions of horizontal rectus muscles have been used to reduce nystagmus amplitude in selected patients.

Results are variable.

Artificial Divergence Surgery

In patients whose nystagmus dampens significantly with convergence, surgery can create a controlled exophoric tendency so that fusional convergence is used to reduce the nystagmus.

This is reserved for carefully selected patients.

Tenotomy and Reattachment

Extraocular muscle tenotomy and reattachment has been investigated as a method of improving:

• Foveation
• Nystagmus intensity
• Visual function

It remains a specialized procedure and is not universally used.

Strabismus Surgery

Associated strabismus may be treated surgically when indicated.

Alignment can also reduce a fusion maldevelopment component in some patients.

Low-Vision Rehabilitation

Patients with significant visual impairment may benefit from:

• Magnification devices
• Electronic aids
• Preferential classroom seating
• Large-print materials
• Low-vision consultation
• Educational accommodations

Genetic Counseling

Consider genetic referral for:

• Family history of nystagmus
• Suspected FRMD7-associated disease
• Albinism
• Retinal dystrophy
• Syndromic disease

Neurology Referral

Neurologic evaluation is appropriate when there are:

• Developmental abnormalities
• Seizures
• Abnormal tone
• Regression
• Vertical or torsional nystagmus
• Opsoclonus
• Other neurologic signs

Follow-Up

Children require periodic ophthalmic evaluation to monitor:

• Visual acuity
• Refractive error
• Amblyopia
• Strabismus
• Head posture
• Underlying ocular disease
• Educational visual needs

School and Development

School performance should be monitored.

Children may have difficulty with:

• Small print
• Distance viewing
• Copying from a board
• Rapid reading
• Visual tasks under time pressure

Appropriate accommodations can significantly improve function.

Prognosis

Visual prognosis depends primarily on the underlying cause.

Isolated infantile nystagmus

Vision may be relatively good.

Sensory-deficit nystagmus

Visual prognosis depends on the underlying retinal, optic nerve, or anterior segment disorder.

Nystagmus often:

• Becomes less noticeable with age
• Persists lifelong
• Rarely disappears completely

Abnormal Head Posture

A compensatory head posture may become more apparent with age as visual demands increase.

Surgery can be helpful when the posture is:

• Large
• Persistent
• Functionally or cosmetically significant

Complications

Potential consequences include:

• Reduced visual acuity
• Amblyopia
• Strabismus
• Abnormal head posture
• Neck discomfort
• Reduced school performance
• Psychosocial impact

Oscillopsia Warning

Classic infantile nystagmus generally does not produce oscillopsia.

New oscillopsia in a patient with longstanding infantile nystagmus should prompt evaluation for:

• Acquired neurologic disease
• New vestibular dysfunction
• Change in the pre-existing ocular motor disorder

Ophthalmology Pearls

• Preferred term: infantile nystagmus syndrome rather than congenital nystagmus.
• INS usually appears during the first 6 months of life, not necessarily at birth.
• Classic INS is usually horizontal, conjugate, and reduced with convergence.
• A null point may produce a compensatory face turn, chin position, or head tilt.
• Patients with infantile nystagmus generally do not experience oscillopsia.
• Always search for a sensory cause such as albinism, foveal hypoplasia, retinal dystrophy, CSNB, optic nerve hypoplasia, cataract, or glaucoma.
• FRMD7 is an important cause of X-linked isolated infantile nystagmus.
• Fusion maldevelopment nystagmus worsens with monocular occlusion and beats toward the fixating eye.
• Spasmus nutans classically causes fine asymmetric nystagmus + head nodding + abnormal head posture and usually improves spontaneously.
• Atypical spasmus nutans, vertical nystagmus, marked asymmetry, neurologic signs, or opsoclonus should prompt neuroimaging/systemic evaluation.
• ERG is especially useful when retinal disease or congenital stationary night blindness is suspected.
• Management starts with optimal refraction, amblyopia therapy, and treatment of the underlying ocular disorder.
• Anderson-Kestenbaum surgery is primarily used to move an eccentric null point toward primary gaze and reduce an abnormal head posture.

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 – 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.

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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.

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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.

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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

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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.

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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

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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.

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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.

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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

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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.

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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.

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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.

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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.

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Stereopsis

Preserved stereopsis provides evidence that both eyes have useful vision.

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

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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.

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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.

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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.

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Visual Field Loss

The most common functional visual field pattern is:

Concentric constriction

sometimes described as:

• Tunnel vision
• Tubular visual field

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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.

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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.

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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.

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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.

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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.

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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.

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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

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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.

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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.

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Functional Ptosis

Features may include:

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

True neurologic and myogenic ptosis must be excluded.

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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.

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Sensory Symptoms

Functional sensory symptoms may include:

• Reduced corneal sensation
• Facial numbness
• Hypersensitivity

These may not respect known neuroanatomic distributions.

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Objective Testing

Objective studies can be useful when the diagnosis remains uncertain.

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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.

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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.

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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.

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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.

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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.

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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