Multiple sclerosis, or MS is a neurological disease where the protective sheaths covering nerve fibers—called “myelin” are damaged. Symptoms include weak limbs, tingling, numbness, fatigue and many visual problems including blurred or double vision. Because symptoms can flare up or go into remission it is difficult to predict the course of the disease. MS can damage the optic nerve causing optic neuritis. In addition, one or both eyes may experience abnormal eye movements called “nystagmus”.
Optic Neuritis
According to the web site All About Multiple Sclerosis, optic neuritis is the most frequently observed symptom of the disease, especially at the onset. Most cases are caused by the process called “demyelination”. The fatty myelin sheaths normally insulate and protect the nerve cells. But as they become inflamed, lesions develop. Gary H.Cassel, M.D., Michael D. Billig, O.D. and Harry G. Randall, M.D. report that a bout of optic neuritis causes an immediate decrease in central vision acuity or visual field. Pain may present as well as eyeball tenderness, colors and lights may dim and the person may have difficulty with depth perception. According to the Multiple Sclerosis International Federation, ON can also cause a large noticeable blind spot in the center of the visual field called a “scotoma”. Most people regain vision and any other residual visual problems is usually mild. However, on rare occasions visual loss may be permanent. There is no one treatment for ON, although steroids may be helpful.
Diplopia
Multiple sclerosis can cause diplopia—or double vision—due to the weakened eye muscles that lose the ability to work well together. According to the Multiple Sclerosis International Federation, diplopia is typically treated with a short course of steroids. In addition, prisms may be prescribed to minimize the double vision. Wearing a patch over one eye also avoids double vision, although this solution impacts depth perception and balance. Fortunately, diplopia is usually temporary. The Multiple Sclerosis Resource Centre reports that diplopia may increase with fatigue or overuse of the eyes and that rest usually alleviates the problem.
Nystagmus
Rhythmic jerky eye movements called “nystagmus” are normal after spinning in circles. However, patients with MS may experience abnormal side to side, up and down or circular eye movements while at rest. With mild cases patients may not be aware of it, although it will be obvious to a medical examiner. According to The Multiple Sclerosis Resource Centre, nystagmus may cause poor vision and often loss of balance. If it interferes with function it may be treated with a muscle relaxant such as botulinum, better known as Botox, or steroids. Experimenting with lighting levels and wearing tinted lenses may help. In addition, since many symptoms of MS are exacerbated by heat, cooling off the body may alleviate nystagmus as well as other visual symptoms.
References
- All About Multiple Sclerosis: Multiple Sclerosis Symptoms
- The Multiple Sclerosis Resource Centre: Visual Disturbances
- Multiple Sclerosis International Federation: Visual Problems
- “The Eye Book”; Gary H. Cassel, M.D., Michael D. Billig, O.D. and Harry G. Randall, M.D.; 1998
