X-linked infantile nystagmus

X-linked infantile nystagmus is a condition characterized by abnormal eye movements. Nystagmus is a term that refers to involuntary side-to-side, up-and-down, or circular movements of the eyes. In people with X-linked infantile nystagmus, the movements are typically side-to-side. In individuals with this condition, nystagmus is present at birth or develops within the first six months of life. 

The abnormal eye movements may worsen when an affected person is feeling anxious or tries to stare directly at an object. Some affected individuals will experience involuntary changes in the direction of their eye movements (periodic alternating nystagmus). The severity of nystagmus varies, even among affected individuals within the same family. Sometimes, affected individuals will turn or tilt their head to compensate for the irregular eye movements. Individuals with X-linked infantile nystagmus may have other eye abnormalities. For example, the region at the back of the eye responsible for sharp central vision may be underdeveloped (foveal hypoplasia).