Vision therapy (also known as vision training, or VT) is used to improve vision skills such as eye movement control, eye coordination, contrast sensitivity, and perception. It primarily focuses on improving visual skills in amblyopia and many binocular vision anomalies including accommodative disorders, vergence disorders, eye movement disorders, and the training of stereopsis. VT involves a series of procedures carried out in both home and office settings, usually under professional supervision by an Optometrist. Orthoptics is a similar discipline, but primarily involves exercises which work on eye alignment for patients with strabismus. Many strabismic surgeons have an orthoptist in-house.
Vision therapy can be prescribed when a comprehensive eye examination indicates that it is an appropriate treatment option. The specific program of therapy is based on the results of standardized tests and the person's signs and symptoms. Programs typically involve eye exercises and the use of lenses, prisms, filters, occluders, specialized instruments, and computer programs. The course of therapy may last weeks to several years, with intermittent monitoring by the eye doctor.
Vision therapy encompasses a wide variety of non-surgical methods to treat disorders of vergence (eye crossing and un-crossing), accommodation (eye focusing and un-focusing), and eye movements (pursuits and saccades). Vergence and accommodation influence eachother through the "Accommodative Convergence / Accommodation" (AC/A) pathway, so disorders of accommodation can often be related to disorders of vergence and vice-versa. Disorders of accommodation and vergence can lead to eyes which appear too crossed or too uncrossed under ordinary situations, eyes which have extra trouble focusing or unfocusing (accommodative hysteresis) under ordinary circumstances, or eyes which feel abnormally strained (asthenopia) when performing tasks that most people have no trouble with.
Accommodative Vergence Disorders
Accommodative Disorders include:
Eye Movement Disorders
Pursuit & Saccadic Eye Movements Disorders include:
Levels of Binocular Sensory Fusion
Amblyopia and Strabismus
Amblyopia (when the brain never learns how to use an eye, also known as a "lazy eye") is a condition which optometric and ophthalmoligical traditions generally agree upon and both treat similarly. Amblyopia, which can also often lead to eyes which do not attend well to visual targets (strabismus, a "turned eye") until the brain can learn to use that eye. Ambloypia is treatable with glasses and eye patching (or drops, sometimes called "wet patching"), to give the best correctable vision possible to the amblyopic eye while blurring the better-seeing eye so that the brain must be forced to use the amblyopic eye ("break suppression") and develop good vision for it. Children, whose brains are still neuroplastic, have better outcomes after amblyopia treatment than adults. Rarely, a child with amblyopia may also have developed a condition known as anomalous sensory correspondence (or [[anomalous correspondence), where the child has learned to attend to visual targets using a part of the retina which is not the central fovea.