is a type of eye
condition where the motion of the eyes are not parallel to each other. This however,only occurs during dissociation of the left eye and right eye, whereby fusion of the eyes is absent. Heterophoria is usually asymptomatic
. This is when it is compensated by fusional vergence
. When fusional reserve is used to compensate for heterophoria, it is known as compensating vergence. In severe cases, when the heterophoria is not overcome by fusional vergence, sign and symptoms appear. This is called decompensated heterophoria.
Heterophoria may lead to squint or also known as strabismus
Etiology of Heterophoria
In order to understand how heterophoria occurs,we must understand of how the eye can maintain proper fixation with non aligned visual axis. Heterophoria is actually the misalignment of the visual axis of both eyes. In other words, one eye or both eyes is not properly fixated to an object of interest. However, we must know that the eyes has a fusional vergence system which corrects this misalignment.
Menifestation of Heterotropia
When the fusional vergence system can no longer hold back heterophoria, the phoria becomes manifest. In this condition, the eyes deviates from the fixating position.
- Animation at mrcophth.com