What is nystagmus? Nystagmus is an involuntary condition in which the eyes make rapid, repeated, uncontrolled movements. These eye movements may be in any direction including horizontally, vertically, or rotationally (in a circle). Many people with nystagmus do not experience visual symptoms. At other times, nystagmus leads to visual problems because the eye cannot maintain steady focus on an object. Children with extremely poor vision may develop nystagmus. Although the exact cause of nystagmus is not known, it is thought to be related to a disorder in the part of the brain that controls eye movement. Nystagmus may be present at birth (congenital nystagmus) and is often inherited or caused by development problems in the visual system. Another variation of nystagmus, called spasmus nutans, usually appears by the age of six months and goes away by itself in early childhood. Nystagmus can also develop at any other point in life, usually as a result of head trauma, stroke, or certain drugs and medications. This type of nystagmus is called acquired nystagmus. In association with uncontrolled eye movements, patients with nystagmus may experience problems with depth perception. The loss of visual acuity and depth perception can also lead to coordination problems. While the exact cause of nystagmus is not well understood, fatigue or increased levels of stress appear to worsen the condition. Congenital or inherited nystagmus is not typically associated with serious medical conditions. However, acquired nystagmus may be a sign of a serious medical condition, including severe head trauma, toxicity, stroke, or inflammatory diseases or other conditions that affect the brain. Seek immediate medical care (call 911) if you, or someone you are with, has a sudden onset of nystagmus. If you have already been diagnosed with nystagmus and it is causing you concern, seek prompt medical care.