Suppression (eye)

Suppression of an eye is a subconscious adaptation by a person's brain to eliminate the symptoms of disorders of binocular vision such as strabismus, convergence insufficiency and aniseikonia. The brain can eliminate double vision by ignoring all or part of the image of one of the eyes. The area of a person's visual field that is suppressed is called the suppression scotoma. Suppression can lead to amblyopia.

Effect

Nobel-prize winner David H. Hubel described suppression in simple terms as follows:
Suppression is frequent in children with anisometropia or strabismus or both. For instance, children with infantile esotropia may alternate with which eye they look, each time suppressing vision in the other eye.

Measurement

During an eye examination, the presence of suppression and the size and location of the suppression scotoma may be the Worth 4 dot test, or with other subjective tests such as the Bagolini striated lens test, or with objective tests such as the 4 prism base out test.

Anti-suppression therapy

Suppression may treated with vision therapy, though there is a wide range of opinions on long-term effectiveness between eye care professionals.

Age factors

Young children with strabismus normally suppress the visual field of one eye, whereas adults who develop strabismus normally do not suppress and therefore suffer from double vision. This also means that adults have a higher risk of post-operative diplopia after undergoing strabismus surgery than young children. Patients who have undergone strabismus surgery at a young age often have monofixation syndrome.