Congenital nystagmus (CN) is an eye movement abnormality that usually begins in infancy. It consists of an involuntary, somewhat rhythmic, oscillation of the eyes that tends to worsen when a person tries to focus (visually) on a target. The most common symptom of CN is poor vision. Since there are numerous causes of poor vision, evaluation by an ophthalmologist or neuro-ophthalmologist is appropriate. The condition is lifelong. Some patients with CN seem to benefit from oral medications (gabapentin or memantine), though these have only been studied in small numbers of patients. Sometimes, patients consider treatment with surgery of extra-ocular muscles.