(n.) A rapid involuntary oscillation of the eyeballs.

Christmas disease Hartnup disease Werdnig-Hoffmann disease achroma achromasia achromatic vision achromatosis albescence albino albinoism astigmatism astigmia bad eyesight blindness blondness blurred vision canescence chalkiness color blindness creaminess cystic fibrosis defect of vision dichromatic vision double sight double vision dysautonomia fairness faulty eyesight frostiness glaucescence glaucousness grizzliness hemophilia hoariness ichthyosis imperfect vision lactescence leukoderma lightness milkiness mongolianism mongolism mucoviscidosis muscular dystrophy nystagmus paleness pancreatic fibrosis partial blindness pearliness reduced sight sickle-cell anemia silver silveriness snowiness thalassemia tunnel vision vitiligo white white race whiteness whitishness