BASICS

DESCRIPTION

• Optic neuritis (ON) is the inflammation of the optic nerve.

• Vision loss is rapid and may be progressive in the first 2–15 days.

• It typically occurs in 1 eye at a time (70%), bilateral occurrence is 30%.

• Optic nerve inflammation and edema at the optic nerve head is termed papillitis.

• If nerve damage is behind the eyeball, it is called retrobulbar neuritis.

Pediatric Considerations

• Optic disc swelling and bilateral disease are more common in children.

• Loss of visual acuity is more severe.

• Recovery of visual acuity is 20/40 or better in 76% of patients.

• Subsequent risk of multiple sclerosis (MS) varies among studies.

Pregnancy Considerations

Management is the same as in the nonpregnant patient.

EPIDEMIOLOGY

• Acute demyelinating ON is the most common cause of unilateral painful visual loss in a young adult.

• Tends to afflict young adults with an average age in their 30s.

• 75% of patients are women.

Incidence

• The annual incidence is 5 per 100,000.

• The incidence is highest in northern countries at higher latitudes.

Prevalence

The prevalence is 115 per 100,000.

RISK FACTORS

• People who are younger than 15 years will acquire the risk of the country to which they migrate.

• 69% of females and 33% of males may develop MS approximately 15 years after the initial attack.

Genetics

No known genetic features of typical ON

PATHOPHYSIOLOGY

An inflammatory process that leads to activation of peripheral T lymphocytes and cause a delayed type of hypersensitivity reaction resulting in demyelination and axonal loss. The recovery can occur with remyelination.

ETIOLOGY

Autoimmune

COMMONLY ASSOCIATED CONDITIONS

Acute demyelinating ON is the initial presentation in approximately 20% of cases of MS.

DIAGNOSIS

The diagnosis of ON is usually made on clinical grounds.

HISTORY

• Sudden onset blurred vision, progressive over a few days to 2 weeks

• Pain with eye movement

• Exacerbation of symptoms with increased body temperature (Uhthoff phenomenon)

• Spontaneous improvement starting within 2–3 weeks

PHYSICAL EXAM

• Impaired vision

• Impaired color vision

• Impaired contrast sensitivity

• Visual field defect mostly central scotoma, or any type

• Optic disc normal (65%) or swollen (35%), pale within 4–6 weeks

• Venous sheathing

• Relative afferent pupillary defect (RAPD)

• Pulfrich phenomenon: The course of a pendulum is perceived as an elliptical movement.

DIAGNOSTIC TESTS & INTERPRETATION

Lab

Initial lab tests

• The yield from diagnostic tests is extremely low in a typical case.

• Ancillary investigations should be done for an alternative diagnosis, if there are atypical features.

Follow-up & special considerations

Appropriate test according to the symptom

Imaging

Initial approach

• Brain MRI with contrast

• Look for hyperintense white matter lesions in T2-weighted images and enhancement of the optic nerve.

• Characteristic demyelinating lesions in patients at risk for MS are 3 mm or larger in diameter, ovoid in shape, and located in periventricular areas

Follow-up & special considerations

• Repeat brain MRI in 3–6 months for new lesions

• Spinal MRI for the presence of demyelinating lesions

Diagnostic Procedures/Other

• Visual evoked potentials (VEP)

• Contrast sensitivity

• Optical coherence tomography (OCT)

• Lumbar puncture (LP) for oligoclonal band, IgG

• Neuromyelitis optica (NMO) (aquaporin 4) antibodies in bilateral or recurrent cases

Pathological Findings

The main pathology is the demyelination and axonal injury of the optic nerve fibers. Remyelination occurs during the recovery phase.

DIFFERENTIAL DIAGNOSIS

• Other inflammatory/vasculitic optic neuropathies (sarcoidosis, systemic lupus erythematosus, Sjögren’s syndrome, Behçet’s syndrome, autoimmune optic neuropathy, chronic relapsing inflammatory optic neuropathy)

• NMO, also known as Devic’s disease should be considered if the ON is bilateral, associated with myelitis and/or there is no visual improvement.

• Infectious ON (tuberculosis, syphilis, Lyme disease, viral disease)

• Postinfections, postvaccination, neuroretinitis

• Ischemic ON (arteritic, nonarteritic)

• Compressive ON (pituitary tumors, glioma, meningioma, craniopharyngioma, aneurysm)

• Toxic (methanol)

• Hereditary (Leber’s hereditary ON)

• Retinal diseases (central serous retinopathy, big blind spot syndrome)

• Functional visual loss

TREATMENT

MEDICATION

First Line

• Corticosteroids are considered for patients with severe visual loss (>20/40) to hasten recovery, but they do not affect the ultimate visual outcome.

• 1 g IV methylprednisolone (MP) per day given for 3 days. An oral taper is not necessary (1).

• Giving oral prednisone alone is contraindicated because of the risk of increasing new attacks.

Second Line

• Treatment with immunomodulators (interferon beta 1a, interferon beta 1b, glatiramer acetate) should be considered for patients with ON whose brain lesions on MRI indicate a high risk of developing clinically definite MS (2).

• Therapies should be individualized and the patient involved in the decision-making process.

ADDITIONAL TREATMENT

General Measures

Review within 1 month is recommended to ensure that vision does not deteriorate after cessation of the treatment.

Pediatric Considerations

• Treatment with IV MP is recommended if visual loss is severe or bilateral.

• Interferon therapy is considered with abnormal MRI of the brain.

Issues for Referral

Neurology consultation for MS evaluation

IN-PATIENT CONSIDERATIONS

Initial Stabilization

IV MP is given as an outpatient.

Admission Criteria

Admission is not necessary for typical ON. Atypical cases can be admitted for work up.

IV Fluids

MP 1 g is given in 500 mL NaCl with slow IV infusion >2 hours.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Follow-up at 1 week, 1 month, 3 months, and then every 6 months for the first 2 years in an asymptomatic patient

PATIENT EDUCATION

Patient should be informed about the disease and the possibility of developing MS.

PROGNOSIS

• Recovery occurs spontaneously within 2–3 weeks in 80%, stabilizing over months to a year.

• 93% had a visual acuity better than 20/40, and 69% had 20/20 vision 1 year following the initial attack (Optic Neuritis Treatment Trial [ONTT])

• The severity of initial visual loss is the only predictor of the final visual outcome.

• Temporal disc pallor develops within 4–6 weeks from the onset and RAPD may disappear when visual recovery is full.

• Anterior optic neuropathy has better prognosis than posterior type.

• 28% and 35% of patients have recurrence of ON within 5 and 10 years, respectively.

• The risk of development of MS after an isolated unilateral ON is 38% at 10 years and 50% at 15 years.

• 75% of female patients and 35% of male patients may ultimately develop MS.

• Treatment does not alter the final visual outcome (3).

• The risk of developing MS is 25% if baseline MRI is normal, and 75% if MRI has one or more MS plaques.

COMPLICATIONS

• Less than 10% of patients may have permanent visual acuity less than 20/40.

• Treatment with IV MP has mainly minor side effects such as transient flushing, a brief disturbance of taste, insomnia, and mild weight gain.

• An anaphylactoid reaction after IV MP treatment has been described in rare cases.

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