الفهرس 
? Anatomy of the extraocular muscles.Only 14 pages are availabe for public view
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Abstract
Strabismus known as ”Heterotropia”,”Squint”, ”Crossed eye”, ”Wondering eye” or” Wall eyed”, is a condition in which the eyes are not properly aligned to 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, preventing proper binocular vision, which may affect depth perception.
It is classified according to many features, including the onset, as it may be child or adult onset, also the relative position of the eye, whether latent or manifest, intermittent or constant, concomitant or incomitant, associated with vertical or horizontal deviations.
This issue, will discuss a special category of squint, named, ”Alphabet patterns” or ”Vertically incomitant-horizontal deviations”, which are defined as: A horizontal misalignment of the eyes in which the magnitude of the horizontal deviation differs in upgaze when compared to downgaze, they are described by letters of alphabet as A-patterns, V-patterns, and less commonly, Y-patterns, Lambda patterns& X-patterns, the letters shapes have visual similarity to the ocular motility pattern, which may be seen with both esotropia & exotropia.
A or V patterns which are more common, occur in about 50% of esotropic or exotropic patients, the more common subtype is V-esotropia, followed by A-esotropia, V-exotropia & A-exotropia.
The etiology of these patterns is not too clear; theories suggesting any of the vertical recti or obliques may be responsible. So their management varies, as it may not be functionally significant & not requiring treatment.
But if it is highly significant, it is managed surgically, as it may cause symptoms as diplopia, manifesting 50% of time or more, producing sensory anomalies or aimed for acquiring normal binocular function & ocular motility for certain professions.
There are many surgical procedures applied, each alternative has got its proponents, some surgeons prefer the vertical muscle surgery as a 1ry procedure, others do it only if the vertical element significant, yet others mainly tackle the horizontal muscle unless the vertical deviation is significant and seems to be primary in nature.