Optic Neuritis

Typical features of Optic Neuritis:

· Sudden loss of vision in one eye – central vision and/or side vision

· Sluggish pupil reaction to light on that side

· Pain around eye or with eye movement (90%)

· Normal (65%) or swollen (35%) optic nerve head

· Young adult patient

· Eventual visual improvement over time (>90%)

Evaluation of typical Optic Neuritis:

· Chest Xray, laboratory tests and lumbar puncture are not necessary for typical Optic Neuritis

· Neuroimaging of the brain by MRI (Magnetic Resonance Imaging) is a powerful predictor of demyelinating disease and should be performed to assess the risk of future neurologic events of Multiple Sclerosis and for treatment decision making.

(Table modified from Lee AG & Brazis PW. Clinical Pathways in Neuro-Ophthalmology: an evidence based approach, Thieme, NY, USA, 1999)

Clinical Trials:

1. Summary of Optic Neuritis Treatment Trial

· High-dose intravenous followed by oral corticosteroids accelerated visual recovery but provided no long-term benefit to vision

· “Standard dose” oral prednisolone alone did not improve the visual outcome and was associated with an increased rate of new attacks of optic neuritis

· Intravenous followed by oral corticosteroids reduced the rate of clinically definite Multiple Sclerosis during the first 2 years (particularly with MRI abnormalities) but by 3 years the treatment effect had subsided

· Treatment was well tolerated with few major side effects

2. Immuno-modulatory therapy such as interferon beta 1-a (Avonex, Biogen), interferon beta 1-b (Betaseron, Berlex) and glatiramer acetate (Copaxone, Teva Marion) has been shown to reduce the relapse rate in established Multiple Sclerosis. The Controlled High-Risk Subject Avonex MS Prevention Study (CHAMPS) studied patients with a first attack of acute clinical demyelinating disease (optic neuritis, incomplete transverse myelitis or brainstem/cerebellar syndrome) and subclinical demyelinating lesions on MRI scanning (two or more high signal white matter abnormalities on T2-weighted images). Patients were treated with intravenous Methyl Prednisolone and half were treated with interferon beta 1-a. The interferon treated group had a 3 year probability of a 44% reduction in the development of definite MS and significant brain MRI signs (relative reduction in the volume of brain lesions, fewer new or enlarging lesions and fewer gadolinium-enhancing lesions) at 18 months. It is suggested that all optic neuritis patients should undergo MRI brain scanning and have neurological evaluation should be sought where appropriate.