Age distribution of the onset of esotropia.

INFORMATION concerning the age distribution of the onset of esotropia is important in several respects, especially in discussing the aetiology of strabismus. Previously, the age distribution was considered to support the refraction theory and later the fusion theory, but more recently it has been considered to support the reflex theory. The child's age at the onset of the strabismus must be taken into account in determining the factors which it is possible to examine directly, and the therapeutic measures which can be employed to counteract it.