Visual Dysfunction in Multiple Sclerosis
Robert Shin, MD
What is optic neuritis?
Patients with multiple sclerosis (MS) can have many different kinds of vision problems, including optic neuritis, diplopia, and nystagmus.
Optic neuritis is blurry vision or hazy vision affecting one eye. It is usually associated with some eye pain or discomfort, especially with eye movements. Often the center of vision is most affected, making it difficult to see people’s faces or creating a “line” in the center of their vision. More than half of all MS patients will experience optic neuritis at one point in their lives. In fact, for 15% to 20% of patients, optic neuritis will be the first presentation of their MS. On examination, a patient with optic neuritis often has an afferent pupillary defect (APD), which is an asymmetry in the two pupils’ reaction to light. Initially, the optic nerve head may look normal or mildly swollen. Later on, the optic nerve may develop pallor (paleness).
The good news is that optic neuritis usually gets better, though the vision in the affected eye may not return 100%. Vision in the affected eye might not be as clear as before, and colors may seem faded or “washed out”. Depth perception is often not as good after an episode of optic neuritis.Return to Top
MS patients are often given intravenous methylprednisolone (also known as Solu-Medrol®) for optic neuritis. The steroids do not appear to improve visual outcome in the end, but they do seem to speed up the recovery of vision.
Double vision, or diplopia, occurs when the eyes are not moving together so that the brain is getting two slightly different pictures simultaneously. This typically occurs when MS affects the brainstem, where the coordination of eye movements is controlled. One common cause of double vision in MS is an internuclear ophthalmoplegia (also known as an INO). Rarely, MS patients may develop double vision from a sixth nerve palsy or other neuro-ophthalmologic disorder.
Sometimes the patient does not see two completely separate images. MS patients may report a “shadow” or a “blur” instead of frank double vision. An important question to ask is whether the visual problem goes away if either eye is closed. Because diplopia is caused by the brain receiving two different images, one from each eye, as soon as either eye is closed, this type of visual problem will go away. On examination, there may be an obvious problem with the movement of the eyes, but sometimes the misalignment is not easy to see without special equipment.
Diplopia often resolves on its own. As with optic neuritis, intravenous corticosteroids are often prescribed, in the hopes of speeding up the recovery. Patients may need to wear an eye patch temporarily. The eye patch is guaranteed to “cure” the diplopia, since only one eye will be sending an image to the brain, but some patients may feel self-conscious while wearing the patch. Sometimes, if recovery is incomplete, eyeglasses with prisms can be used to bring the eyes back into alignment. Prism eyeglasses are similar to prescription eyeglasses for reading. The prism prescription and can be added to an already existing eyeglass prescription. In rare cases, strabismus surgery (surgery to correct crossed eye) may be recommended to realign the eyes.
Nystagmus is an involuntary, rhythmic movement of the eyes that can be associated with vertigo (a feeling of “dizziness”), oscillopsia (the illusion that the world is “jumping” or “swinging back and forth”), blurry vision, or diplopia. Nystagmus can occur in the setting of an internuclear ophthalmoplegia (INO), or due to a MS attack in the vestibular part of the brainstem or cerebellum.
The nystagmus may be visible when the patient is looking straight ahead, but sometimes is only present when the patient is looking off to the side, up, or down. If the nystagmus is very mild, it may only be perceptible while using an ophthalmoscope.
Nystagmus can be difficult to treat if it does not resolve on its own. Various medications may help dampen down the nystagmus, including clonazepam (Klonopin®), baclofen (Lioresal®), gabapentin (Neurontin®), and memantine (Namenda®). In rare instances, surgery or botulinum toxin (Botox®) may help.
In summary, vision can be impaired by MS in many different ways. MS patients with visual problems may benefit from an evaluation by both a neurologist and an ophthalmologist, or a neuro-ophthalmologist if one is available. An accurate analysis of the exact visual problem will help lead to possible treatment options.
Date posted: May 2007