The reduced visual acuity may result in difficulty in school, such as inability to read what is written on a chalkboard except when very close, and difficulty with ball sports. It may also result in inability to drive and place limitation on vocational choice. Movements may be horizontal, vertical, oblique, rotary, circular, or any combination of these. The defect is classified according to the position of the eyes when it occurs. The cause of nystagmus is unknown.
Reduced acuity is caused by the inability to maintain steady fixation.
Head nodding often accompanies congenital nystagmus. Nystagmus may be induced with an optokinetic drum or through the stimulation of the semicircular canals. Glaucoma Glaucoma is not a single disease but a group of conditions with various causes that ultimately are associated with progressive damage to the optic nerve and subsequent loss of visual function. Glaucoma is the third most common cause of blindness in the United States with over 80,000 Americans blind from Glaucoma. It has been estimated that less than half the patients who have glaucoma have actually been diagnosed as having glaucoma.