Exophoria

Overview
Exophoria is a form of heterophoria in which there is a tendency of the eyes to deviate outward.

Prevalence
Exophoria is particularly common in infancy and childhood, and increases with age.

Cause
Exophoria can be caused by several factors, which include:


 * Refractive errors - distance and near deviation approximately equal.
 * Divergence excess - exodeviation is more than 15 dioptres greater for distance than near deviation.
 * Convergence insufficiency - near exodeviation greater than distance deviation.

These can be due to nerve, muscle, or congenital problems, or due to mechanical anomalies. Unlike exotropia, fusion is possible in this condition, causing diplopia to be uncommon.