Picture: Quick Reference Neuroscience Second Edition by Sharon A. Gutman
Generally speaking, in Multiple Sclerosis, there are two types of nystagmus; vertical and horizontal. Of coarse you can have a combination of both but what is Nystagmus? Ever notice that when you scan your eyes from left to right/right to left or up and down that they seem to quickly jump, skip, or shake? Is it hard to focus on a stationary object because it seems to be skipping around a bit? Nystagmus is a quick involuntary back and forth skipping/jerking of the eye. Nystagmus (in MS) may be caused by a lesion in the part of the brain that controls eye movement. In some cases, nystagmus can be caused also be caused by Ataxia. This is externally visible meaning, other people can see your eyes skipping or if you were to film yourself (like I have in the past; seen below) you can see it yourself while trying to slowly scan your eyes horizontally or vertically.