Optic neuritis is inflammation of the optic nerve. Symptoms are usually unilateral, with eye pain and partial or complete vision loss. Diagnosis is primarily clinical. Treatment is directed at the underlying condition; most cases resolve spontaneously.
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:
Neuromyelitis optica (NMO) (1)
Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) (2)
Infectious diseases (eg, viral encephalitis [particularly in children], sinusitis, meningitis, tuberculosis [TB], syphilis, human immunodeficiency virus [HIV])
Tumor metastasis to the optic nerve
Systemic lupus erythematosus
Rare causes include pernicious anemia and systemic autoimmune diseases. Often, the cause remains idiopathic despite thorough evaluation.
General references
1. Chen JJ, Pittock SJ, Flanagan EP, et al: Optic neuritis in the era of biomarkers. Surv Ophthalmol 65(1):12-17, 2020. doi: 10.1016/j.survophthal.2019.08.001
2. Chen JJ, Bhatti MT: Clinical phenotype, radiological features, and treatment of myelin oligodendrocyte glycoprotein-immunoglobulin G (MOG-IgG) optic neuritis. Curr Opin Neurol 33(1):47-54, 2020. doi: 10.1097/WCO.0000000000000766
Symptoms and Signs of Optic Neuritis
The main symptom of optic neuritis is vision loss, frequently maximal within several 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.
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, but this is rare for most cases of optic neuritis.
Diagnosis of Optic Neuritis
Clinical evaluation
Magnetic resonance imaging (MRI)
Optic neuritis is suspected in patients with characteristic pain and vision loss, particularly if they are young. Neuroimaging, preferably with gadolinium-enhanced MRI of the brain and orbits, is usually done and may show an enlarged, enhancing optic nerve. MRI may also help diagnose multiple sclerosis, myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and neuromyelitis optica (NMO). There is usually more extensive enhancement of the optic nerve(s) in NMO and MOGAD. Fluid attenuating inversion recovery (FLAIR) MRI sequences may show typical demyelinating lesions in a periventricular location if optic neuritis is related to multiple sclerosis. Spinal cord involvement can be seen in any of the demyelinating diseases but is usually more extensive in NMO and MOGAD. NMO and MOG antibodies in the serum should be checked for any atypical or severe optic neuritis.
Pearls & Pitfalls
|
Prognosis for Optic Neuritis
Prognosis depends on the underlying condition. Most episodes of typical optic neuritis improve spontaneously with significant recovery of vision in 2 to 3 months. The recurrence rate among patients with optic neuritis is variable and depends on the etiology. Patients with an underlying disease, such as NMO or MOGAD, have higher rates of recurrence in the same eye or in the other eye, and recovery of vision can be worse, especially for NMO (1). MRI is used to determine future risk of demyelinating disease, especially multiple sclerosis.
Prognosis reference
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
Treatment references
1. Morrow SA, Fraser JA, Day C, et al: Effect of treating acute optic neuritis with bioequivalent oral vs intravenous corticosteroids: A randomized clinical trial. JAMA Neurol 75(6): 690-696, 2018. doi: 10.1001/jamaneurol.2018.0024
2. Chen JJ, Pittock SJ, Flanagan EP, et al: Optic neuritis in the era of biomarkers. Surv Ophthalmol 65(1):12-17, 2020. doi: 10.1016/j.survophthal.2019.08.001
Key Points
Optic neuritis is most common among adults 20 to 40 years.
The most common causes are demyelinating diseases, particularly multiple sclerosis, neuromyelitis optica (NMO), and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD), but infections, drugs, and toxins are other possible causes.
Findings include mild pain with eye movement, visual disturbances (particularly disproportionate loss of color vision), and afferent pupillary defect.
Do gadolinium-enhanced MRI of the brain and orbits. Do MRI of the spinal cord if multiple sclerosis is suspected.
Corticosteroids and other treatments can be given, particularly if demyelinating disease is suspected. Plasma exchange is often given for NMO attacks or severe attacks that are unresponsive to high-dose corticosteroids.
