Monofixation syndrome (MFS) (also: microtropia or microstrabismus) is an eye condition defined by less-than-perfect

binocular vision In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an ...

. It is defined by a small angle deviation with suppression of the deviated eye and the presence of binocular peripheral fusion. That is, MFS implies peripheral fusion without central fusion. Aside the manifest small-angle deviation ("tropia"), subjects with MFS often also have a large-angle latent deviation (''phoria''). Their

stereoacuity Stereoscopic acuity, also stereoacuity, is the smallest detectable depth difference that can be seen in binocular vision. Specification and measurement Stereoacuity is most simply explained by considering one of its earliest test, a two-peg devic ...

is often in the range of 3000 to 70 arcsecond, and a small central suppression scotoma of 2 to 5 deg. A rare condition, MFS is estimated to affect only 1% of the general population. There are three distinguishable forms of this condition: primary constant, primary decompensating and consecutive MFS. It is believed that primary MFS is a result of a primary sensorial defect, predisposing to

anomalous retinal correspondence Retinal correspondence is the inherent relationship between paired retinal visual cells in the two eyes. Images from one object stimulate both cells, which transmit the information to the brain, permitting a single visual impression localized in t ...

. Secondary MFS is a frequent outcome of surgical treatment of

congenital esotropia Infantile esotropia is an ocular condition of early onset in which one or either eye turns inward. It is a specific sub-type of esotropia and has been a subject of much debate amongst ophthalmologists with regard to its naming, diagnostic features ...

. A study of 1981 showed MFS to result in the vast majority of cases if surgical alignment is reached before the age of 24 months and only in a minority of cases if it is reached later. Cited according to: MFS was first described by

Marshall Parks Marshall Miller Parks (July 6, 1918 – July 25, 2005) was an American ophthalmologist known to many as "the father of pediatric ophthalmology".Joe Holley"D.C. Physician Illuminated The Ailments of Young Eyes."''Washington Post''. Sunday, August 2 ...

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{{Eye pathology Disorders of ocular muscles, binocular movement, accommodation and refraction Syndromes de:Mikrostrabismus