The visual symptoms that occur in MS may be the result of optic neuritis — inflammation of the optic nerve — or lesions (damaged areas) along the nerve pathways that control eye movements and visual coordination. Optic neuritis may result in blurring or graying of vision, or blindness in one eye. A scotoma or dark spot may occur in the center of the visual field.
Optic neuritis is almost always self-limiting, and affected individuals generally make a good recovery. Studies suggest that treatment with intravenous methylprednisolone, sometimes followed by a tapered course of oral steroids, may be useful.
Nystagmus, or uncontrolled horizontal or vertical eye movements, may be mild — only occurring when the person looks to the side — or it may be severe enough to impair vision. Some medications and special prisms have been reported to be successful in treating the visual deficits caused by nystagmus and a related eye-movement disorder, opsoclonus, which causes "jumping vision."
Diplopia, or double vision, occurs when the pair of muscles that control a particular eye movement are not perfectly coordinated due to weakness in one or both pairs of muscles. When the images are not properly fused, the person perceives a false double image. Double vision may increase with fatigue or overuse of the eyes (e.g., with extended reading or computer work), and improve with rest. Resting the eyes periodically throughout the day can be beneficial.
Diplopia usually resolves without treatment. In some cases, a brief course of corticosteroids may be helpful. Patching one eye can also be useful for driving or other short tasks, but is not recommended for long periods of time since it will slow the brain's ability to accommodate to the problem. Special lenses are rarely recommended because the symptom tends to be transitory.
These various visual symptoms are common in people with MS, but rarely result in total blindness.