Nystagmus, Congenital

Strabismus (misalignment of the eyes) often runs in families. In this study, the investigators are looking for genetic variants associated with strabismus and nystagmus. Three types of subects will be enrolled: (1) Families with at least 3 members with strabismus, (2) individuals with infantile esotropia and their parents and siblings, and (3) individuals with infantile nystagmus and their parents. Whole exome and/or whole genome sequencing will be used to identify genetic variants shared by family members with strabismus and to identify genetic causes of nystagmus.