Ophthalmology – Neuroretinitis

Basics

Description

Neuroretinitis is an inflammatory optic neuropathy characterized by:

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

It is usually:

• Unilateral
• Painless
• Self-limited in immunocompetent patients

Bilateral disease can occur but is less common.

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

The most important infectious association is:

Bartonella henselae – cat-scratch disease

Epidemiology

Neuroretinitis:

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

The true prevalence is uncertain.

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

Risk Factors

Important historical risk factors include:

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

A viral-like illness may precede otherwise idiopathic neuroretinitis.

Pathophysiology

The characteristic process begins with inflammation and leakage from the:

Optic nerve head

This causes:

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

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

Macular star

Macular Star Formation

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

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

Therefore:

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

Etiology

Neuroretinitis may be:

• Infectious
• Postinfectious
• Immune-mediated
• Idiopathic

Infectious Causes

Important infectious causes include:

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

Other infectious etiologies should be considered according to:

• Geography
• Exposure history
• Immune status

Bartonella henselae

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

It causes cat-scratch disease.

Transmission commonly involves:

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

A scratch is not always recalled.

Cat-Scratch Disease

Systemic manifestations may include:

• Fever
• Malaise
• Headache
• Regional lymphadenopathy

Ocular manifestations can include:

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

Diagnosis

Diagnosis is based on the characteristic combination of:

Optic disc edema + delayed macular star formation

together with clinical and laboratory evaluation for an underlying cause.

History

Patients commonly report:

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

Vision may range from near normal to profound impairment.

Pain

Unlike typical demyelinating optic neuritis:

Neuroretinitis is usually painless.

Pain with eye movement is less characteristic.

Systemic Symptoms

Ask about:

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

Physical Examination

Visual Acuity

Visual acuity may range widely depending on:

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

Pupillary Examination

A unilateral or asymmetric case usually produces a:

Relative afferent pupillary defect

Color Vision

Acquired dyschromatopsia is common.

Patients may have:

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

Optic Disc

Typical initial finding:

Optic disc edema

This may be:

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

Macular Star

The hallmark finding is:

Radially arranged hard exudates around the fovea

forming a star-shaped pattern.

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

Chorioretinal Lesions

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

Visual Field Defects

Possible defects include:

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

The most typical pattern is central or cecocentral involvement.

Bilateral Disc Edema

Bilateral neuroretinitis is possible.

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

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

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

Diagnostic Testing

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

Bartonella Serology

When cat-scratch disease is suspected, obtain:

• Bartonella henselae IgG
• Bartonella henselae IgM

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

Serology must be interpreted in clinical context.

Additional Laboratory Tests

Depending on the presentation, evaluation may include:

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

Autoimmune studies should be guided by systemic findings.

Syphilis

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

Testing generally includes:

• Treponemal test
• Nontreponemal test

Ocular syphilis requires systemic treatment.

Tuberculosis

Consider tuberculosis when there is:

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

Testing may include:

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

MRI

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

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

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

Optical Coherence Tomography

OCT is very useful for documenting:

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

Serial OCT is useful for monitoring recovery.

Fluorescein Angiography

FA typically demonstrates:

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

It may also identify:

• Retinal vascular inflammation
• Focal chorioretinal lesions
• Macular leakage

Fundus Photography

Useful for documenting:

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

Visual Field Testing

Formal visual fields are useful for:

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

Differential Diagnosis

Important differential diagnoses include:

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

Hypertensive Retinopathy

Severe hypertension can produce:

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

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

Neuroretinitis vs Typical Optic Neuritis

Neuroretinitis

Usually:

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

Typical Demyelinating Optic Neuritis

Usually:

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

Treatment

Treatment depends on the underlying cause.

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

Self-limited

and recover spontaneously.

Bartonella-Associated Neuroretinitis

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

Treatment is more strongly considered when there is:

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

Antibiotic Therapy

Antibiotics used for Bartonella infection may include:

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

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

Doxycycline with rifampin

for several weeks.

Treatment should be individualized according to:

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

Immunocompromised Patients

Patients who are immunocompromised generally require treatment because they have:

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

Corticosteroids

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

However:

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

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

Cause-Specific Treatment

If another infectious cause is identified, treat appropriately.

Examples include:

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

Referral

Patients should be evaluated by an:

• Ophthalmologist

Referral to a:

• Neuro-ophthalmologist
• Retina/uveitis specialist

is appropriate when:

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

Infectious disease consultation may be useful for complex infections.

Hospitalization

Most uncomplicated neuroretinitis can be treated as an outpatient.

Admission may be required for:

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

Follow-Up

During the acute phase, follow-up should monitor:

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

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

Natural Course

Optic disc swelling generally resolves first.

Macular exudates may persist considerably longer.

They often resolve over:

Several months

and occasionally remain visible for many months.

Patient Education

Patients should understand that:

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

Cat-Exposure Education

When Bartonella infection is suspected or confirmed:

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

Cat ownership itself usually does not need to be eliminated.

Prognosis

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

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

Recovery may continue even while the macular star remains visible.

Poor Prognostic Factors

Residual impairment is more likely with:

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

Complications

Potential complications include:

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

Ophthalmology Pearls

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