Refraction and muscular imbalance, as simplified through the use of the ski-optometer

by Daniel Woolf

Binocular Fixation

We habitually use the eyes together, fixating with both at once; that is, we direct the eyes in such a way that the image of the object to which the attention is directed falls on the fovea of each eye.

Where both eyes are accurately directed to an object at which one or both are looking, the condition is known as “binocular fixation,” which is commonly understood to mean that both eyes are straight.

The ability to produce and maintain binocular fixation—to keep both eyes directly straight—is acquired early in life. The impulse to maintain it grows with exercise, and soon becomes so strong that after the age of infancy binocular fixation is present in the great majority of persons, and in most of them is present all the time.

Binocular fixation must be distinguished through three conditions—orthophoria, heterophoria and squint.