Optic neuritis (ON)

Optic neuritis (ON) is an inflammation of the optic nerve that typically presents in adults between the ages of 20 and 40. It is generally of infectious (measles, chickenpox, mumps, herpes, Epstein-Barr virus [EBV; infectious mononucleosis], human immunodeficiency virus [HIV; AIDS] or cytomegalovirus [CMV]) or autoimmune (sarcoidosis, lupus, etc.) origin. Isolated forms with no identifiable cause have also been reported.

Optic neuritis is the most common manifestation of neuromyelitis optica spectrum disorder (NMOSD; read more here) before the age of 40, as well as of MOG antibody-associated disease (MOGAD, read more here).

 

What are the symptoms of optic neuritis?

Symptoms appear suddenly, in a matter of hours or days, and can rapidly worsen to the point of near blindness. Initially, patients generally experience localized pain at the back of the eye, which intensifies with eye movements. Various visual symptoms can then occur in one eye, or more rarely in both eyes. These include reduced visual acuity (decreased vision) of varying severity, visual field abnormalities (impression of having a black or blurred spot in the field of vision), and color and/or contrast vision abnormalities.

How is optic neuritis diagnosed?

Diagnosis is based on the clinical analysis of symptoms and their sudden onset, as well as a full ophthalmological examination. Magnetic resonance imaging (MRI) of the brain is also performed to examine the optic nerve. A lumbar puncture may help clarify the diagnosis and further tests (including blood tests) are needed to determine the cause of the optic neuritis and whether this first episode will remain isolated or if it is the first attack of an inflammatory disease of the central nervous system, such as multiple sclerosis (MS), NMOSD, or another autoimmune disease.

Treatment must be rapidly initiated in order to limit the risk of sequelae.

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