Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS). The CNS includes the brain, spinal cord, and optic nerves.
MS is characterized by the immune system damaging myelin — a substance that surrounds and protects nerve fibers. Damaged areas of myelin are referred to as plaques or lesions.
Demyelinating lesions can affect different parts of the CNS, including the optic nerves. One of the common early signs of MS is vision problems.
People with MS sometimes experience myoclonus. Myoclonus is sudden, involuntary twitching or quivering of a muscle or group of muscles.
It’s a reactive nerve cell misfire that sends the wrong signal to your muscles. This could be the result of demyelinating lesions from MS.
There are a variety of causes for an eye twitch in people with MS, such as nystagmus and internuclear ophthalmoplegia. Other eye conditions such as optic neuritis and diplopia are also known to affect many people with MS.
Nystagmus is uncontrolled repetitive vertical, horizontal, or circular eye movements. This makes it nearly impossible to steadily view objects.
Acquired nystagmus is not an uncommon symptom of MS, and often results in diminished vision and depth perception. It also can impact coordination and balance.
If you have visually disabling nystagmus, your doctor might recommend medications such as:
Internuclear ophthalmoplegia (INO) is damage to the nerve fibers that coordinate both eyes in looking from side to side (horizontal movements). Vertical eye movements are not affected.
If INO is caused by a stroke (typically in older people), it usually only affects one eye. If it’s caused by MS (typically in younger people), it often affects both eyes.
For acute internuclear ophthalmoplegia, your doctor might recommend intravenous steroid therapy.
A common vision problem related to MS, optic neuritis is an inflammation of the optic nerve that can result in blurred vision, pain, and a sudden loss of vision — typically in one eye.
Rarely causing blindness, optic neuritis might result in the blurring of vision or a dark spot in the center of the visual field, known as a central scotoma.
Optic neuritis commonly improves on its own, but based on your specific situation, your doctor might recommend a steroid such as methylprednisolone administered intravenously, possibly followed with oral steroids.
Diplopia is also known as double vision. It occurs when the pair of muscles that control a particular eye movement weaken and become uncoordinated.
When the images are not properly aligned, it results in a double image. Fatigue and overuse of the eyes can increase the effects of diplopia. Double vision may increase with fatigue or overuse of the eyes.
Diplopia is often transitory and resolves without treatment. Your doctor might recommend a short treatment with corticosteroids.
The first step for treating any eye movement abnormality is to speak with your neurologist. If your neurologist is an MS specialist or has been trained in neuro-ophthalmology, they will evaluate your condition and create a treatment plan. If they do not have a neuro-ophthalmology background, they may refer you to an optometrist or ophthalmologist.