Q: I have either PPMS or SPMS, and my opthalmologist just checked my eyes and said that I have pale optic nerves. This is something new, since I get my eyes checked by this retinal specialist every year. Several years before I was diagnosed with MS, I had a bout of tunnel vision that lasted for a few months, but am not sure if that was a relapse. Could these two things relate? Am I in danger of losing my vision? What do I do?
A: Optic nerve pallor is a finding on examination with many causes. The normal optic disc has a pink coloration from the small blood vessels supplying the nerve head and adjacent retina. When there is permanent damage to the nerve fibers traveling through the disc there is also a loss of these small blood vessels resulting in a characteristic white or pale coloration to some or all of the optic nerve head. By the way this is the only part of your central nervous system that we can actually see without opening your skull, so it is an important part of the examination.
Optic nerve pallor can be difficult to detect early, particularly when the process involves both eyes. At this stage it usually requires special equipment to detect. Eventually, the change in coloration becomes obvious even when when involving both eyes. Optic nerve pallor is a sign of a disease not a problem by itself. It is not unusual for MS patients to have significant optic nerve atrophy but preserved visual acuity (the ability to see objects of smaller and smaller size with maximal contrast). However, there is usually a loss of low contrast vision, especially in low light situations, and some alteration of color vision (reds appear dull). Special testing often reveals areas in your field of vision that are worse than others called a visual field defect. While it is possible for a person with MS to eventually become blind from progressive optic atrophy this is less common than one would expect.
There are other causes of optic atrophy, even in a patient with known multiple sclerosis, and an ophthalmologist is the correct person to see if there is anything atypical about the optic atrophy. Before MRI scans were available, optic nerve atrophy was considered one of the diagnostic hallmarks of MS; in fact if you saw a person with longstanding MS without optic nerve pallor, physicians were taught to re consider the diagnosis of MS. There is no specific treatment to prevent further optic nerve atrophy if it is caused by multiple sclerosis. There are some other treatable causes such as smoking and B vitamin deficiencies. It is essential to quit smoking as soon as possible and take a multivitamin daily. You neurologist can talk to you about other possible causes but ask him or her to focus on the treatable conditions.
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