Etiology of Optic Neuritis
Optic neuritis is most common among adults 20 to 40 years. Most cases result from demyelinating disease, particularly multiple sclerosis, in which case there may be recurrences. Optic neuritis is often the presenting manifestation of multiple sclerosis. Other causes include:
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Infectious diseases (eg, viral encephalitis [particularly in children], sinusitis, meningitis, tuberculosis [TB], syphilis, human immunodeficiency virus [HIV])
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Tumor metastasis to the optic nerve
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Chemicals and drugs (eg, lead, methanol, quinine, arsenic, ethambutol, antibiotics)
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Neuromyelitis optica (NMO) (1)
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Myelin oligodendrocyte glycoprotein autoantibody (MOG-IgG) disease (2)
Rare causes include diabetes, pernicious anemia, systemic autoimmune diseases, Graves ophthalmopathy, bee stings, and trauma. Often, the cause remains obscure despite thorough evaluation.
General references
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1. Pittock SJ and Luccienetti CF: Neuromyelitis optica and the evolving spectrum of autoimmune aquaporin-4 channelopathies: A decade later. Ann NY Acad Sci 1366(1)20-39, 2016. doi: 10.1111/nyas.12794.
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2. Chen JJ, Flanagan EP, Jitprapaikulsan J, et al: Myelin oligodendrocyte glycoprotein antibody-positive optic neuritis: Clinical characteristics, radiologic clues, and outcome. Am J Ophthalmol195:8-15, 2018. doi: 10.1016/j.ajo.2018.07.020.
Symptoms and Signs of Optic Neuritis
The main symptom of optic neuritis is vision loss, frequently maximal within 1 or 2 days and varying from a small central or paracentral scotoma to complete blindness. Most patients have mild eye pain, which often feels worse with eye movement.
If the optic disk is swollen, the condition is called papillitis. If the optic disk appears normal, the condition is called retrobulbar neuritis. The most characteristic findings include reduced visual acuity, a visual field deficit, and disturbed color vision (often out of proportion to loss of visual acuity). An afferent pupillary defect is usually detectable if the contralateral eye is unaffected or involved to a lesser degree. Testing of color vision is a useful adjunct, although 10% of males have congenital color blindness, producing false-positive results. In about two thirds of patients, inflammation is entirely retrobulbar, causing no visible changes to the optic nerve head. In the rest, disk hyperemia, edema in or around the disk, vessel engorgement, or a combination is present. A few exudates and hemorrhages may be present near or on the optic disk.
Diagnosis of Optic Neuritis
Optic neuritis is suspected in patients with characteristic pain and vision loss, particularly if they are young. Neuroimaging, preferably with gadolinium-enhanced MRI, is usually done and may show an enlarged, enhancing optic nerve. MRI may also help diagnose multiple sclerosis, myelin oligodendrocyte glycoprotein autoantibody (MOG-IgG) disease, and neuromyelitis optica (NMO). Fluid attenuating inversion recovery (FLAIR) MRI sequences may show typical demyelinating lesions in a periventricular location if optic neuritis is related to demyelination. Spinal cord involvement can be seen in NMO or MOG-IgG disease.
Prognosis for Optic Neuritis
Prognosis depends on the underlying condition. Most episodes resolve spontaneously, with return of vision in 2 to 3 months. Most patients with a typical history of optic neuritis and no underlying systemic disease, such as a connective tissue disease, recover vision, but > 25% have a recurrence in the same eye or in the other eye (1). MRI is used to determine future risk of demyelinating disease.
Prognosis reference
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1. Beck RW, Cleary PA, Backlund JYC, Optic Neuritis Study Group: The course of visual recovery after optic neuritis: Experience of the optic neuritis treatment trial. Ophthalmology 127(4S):S174-S181, 2020. doi: 10.1016/j.ophtha.2020.01.027.
Treatment of Optic Neuritis
Corticosteroids are an option, especially if multiple sclerosis or neuromyelitis optica are suspected. Treatment with methylprednisolone (500 mg to 1000 mg intravenously once a day) for 3 days followed by prednisone (1 mg/kg orally once a day) for 11 days may speed recovery, but ultimate vision results are no different from those with observation alone. Intravenous corticosteroids have been reported to delay onset of multiple sclerosis for at least 2 years. Treatment with oral prednisone alone does not improve vision outcome and may increase the rate of recurrent episodes. Low-vision aids (eg, magnifiers, large-print devices, talking watches) may be helpful. Other treatments, such as those used to treat multiple sclerosis, can be given if multiple sclerosis is suspected.
Key Points
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Optic neuritis is most common among adults 20 to 40 years.
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The most common causes are demyelinating diseases, particularly multiple sclerosis, neuromyelitis optica (NMO), and myelin oligodendrocyte glycoprotein autoantibody (MOG-IgG) disease, but infections, tumors, drugs, and toxins are other possible causes.
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Findings include mild pain with eye movement, visual disturbances (particularly disproportionate loss of color vision), and afferent pupillary defect.
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Consider gadolinium-enhanced MRI.
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Corticosteroids and other treatments can be given, particularly if multiple sclerosis is suspected.
Drugs Mentioned In This Article
| Drug Name | Select Trade |
|---|---|
methylprednisolone |
MEDROL |
prednisone |
RAYOS |
ethambutol |
MYAMBUTOL |
quinine |
QUALAQUIN |
