Suppression of an

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

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

binocular vision Binocular vision is seeing with two eyes. The Field_of_view, field of view that can be surveyed with two eyes is greater than with one eye. To the extent that the visual fields of the two eyes overlap, #Depth, binocular depth can be perceived. Th ...

such as

strabismus Strabismus is an eye disorder in which the eyes do not properly align with each other when looking at an object. The eye that is pointed at an object can alternate. The condition may be present occasionally or constantly. If present during a ...

convergence insufficiency Convergence insufficiency is a sensory and neuromuscular anomaly of the binocular vision system, characterized by a reduced ability of the Human eyes, eyes to turn towards each other, or sustain Convergence (eye), convergence. Symptoms The sympto ...

and

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. If the ocular image size in both ...

. 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 (with a

scotoma A scotoma is an area of partial alteration in the field of vision consisting of a partially diminished or entirely degenerated visual acuity that is surrounded by a field of normal – or relatively well-preserved – vision. Every normal mamm ...

meaning, more generally, an area of partial alteration in the visual field). Suppression can lead to

amblyopia Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amb ...

Effect

Nobel-prize winner

David H. Hubel David Hunter Hubel (February 27, 1926 – September 22, 2013) was an American Canadian neurophysiologist noted for his studies of the structure and function of the visual cortex. He was co-recipient with Torsten Wiesel of the 1981 Nobel Pr ...

described suppression in simple terms as follows: :"Suppression is familiar to anyone who has trained himself to look through a monocular microscope, sight a gun, or do any other strictly one-eye task, with the other eye open. The scene simply disappears for the suppressed eye."

: ''Eye, Brain, and Vision'', Chapter 9 "Deprivation and development"
section "Strabismus"
Published online by Harvard Medical School (downloaded 30 September 2014) Suppression is frequent in children with

anisometropia Anisometropia is a condition in which a person's eyes have substantially differing refractive power. Generally, a difference in power of one diopter (1D) is the threshold for diagnosis of the condition. Patients may have up to 3 diopters of anis ...

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 An eye examination, commonly known as an eye test, is a series of tests performed to assess Visual acuity, vision and ability to Focus (optics), focus on and discern objects. It also includes other tests and examinations of the human eye, eyes. ...

, the presence of suppression and the size and location of the suppression scotoma may be the Worth 4 dot test (a subjective test that is considered to be the most precise suppression 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 Vision therapy (VT), or behavioral optometry, is an umbrella term for alternative medicine treatments using eye exercises, based around the pseudoscientific claim that vision problems are the true underlying cause of learning difficulties, partic ...

, 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 (or part of it), whereas adults who develop strabismus normally do not suppress and therefore suffer from double vision (

diplopia Diplopia is the simultaneous perception of two images of a single object that may be displaced in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often voluntary. However, when occ ...

). This also means that adults (and older children) have a higher risk of post-operative diplopia after undergoing

strabismus surgery Strabismus surgery (also: ''extraocular muscle surgery'', ''eye muscle surgery'', or ''eye alignment surgery'') is surgery on the extraocular muscles to correct strabismus, the misalignment of the human eye, eyes. Strabismus surgery is a one-day ...

than young children. Patients who have undergone strabismus surgery at a young age often have monofixation syndrome (with peripheral binocular fusion and a central suppression scotoma).

References

{{reflist * Carlson, NB, et al. ''Clinical Procedures for Ocular Examination. Second Ed.'' Mc Graw-Hill. New York 1996. Human eye Binocular rivalry

Effect

Measurement

Anti-suppression therapy

Age factors

See also

References