Suppression of an eye

Human eye

The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

 is a subconscious adaptation by a person's brain to eliminate the symptoms of disorders of binocular vision

Binocular vision

Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a...

 such as strabismus

Strabismus

Strabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...

, convergence insufficiency

Convergence insufficiency

Convergence insufficiency or Convergence Disorder is a sensory and neuromuscular anomaly of the binocular vision system, characterized by an inability of the eyes to turn towards each other, or sustain convergence.-Symptoms:...

 and aniseikonia

Aniseikonia

Aniseikonia is an ocular condition where there is a significant difference in the perceived size of images. It can occur as an overall difference between the two eyes, or as a difference in a particular meridian.-Causes:Retinal image size is determined by many factors...

. The brain can eliminate double vision by ignoring the images of one of the eyes. This can lead to Amblyopia

Amblyopia

Amblyopia, also known as lazy eye, is a disorder of the visual system that is characterized by a vision deficiency in an eye that is otherwise physically normal, or out of proportion to associated structural abnormalities of the eye...

.

During an eye examination

Eye examination

An eye examination is a battery of tests performed by an ophthalmologist, optometrist, or orthoptist assessing vision and ability to focus on and discern objects, as well as other tests and examinations pertaining to the eyes....

, suppression may be evaluated with tests such as the Worth 4 dot test

Worth 4 dot test

The Worth 4 dot test, also known as the Worth Lights test, is a clinical test for suppression of either the right or left eye. Suppression occurs during binocular vision when the brain does not process the information received from either of the eyes...

, and the 4 prism Base out test.

Suppression may treated with vision therapy

Vision therapy

Vision therapy, also known as visual training, vision training, or visual therapy, is a broad group of techniques aimed at correcting and improving binocular, oculomotor, visual processing, and perceptual disorders."-Historical development:...

, though there is a wide range of opinions on long-term effectiveness between eye care professionals, with little scientific evidence of long-term improvement of suppression, if the underlying cause is not addressed (strabismus, amblyopia, etc.).