When eyes are misaligned or are not looking at the same place at the same time, it is a condition called strabismus, commonly referred to as 'lazy eye.' The name is derived from the Greek word, 'strabismos', which means to squint. Many patients with strabismus will squint on occasion, especially in bright light outdoors.
Types of Strabismus
Many people think that strabismus is the result of an eye muscle problem, but in most instances, the eye muscles are quite healthy. Most of the time, the problem lies in the part of the brain that controls fusion, or keeping both eyes simultaneously directed toward the object of interest. Some forms of strabismus are the result of abnormally functioning eye muscles, or nerves that stimulate an eye muscle; this is known as paralytic strabismus because a muscle is believed to be paralyzed. There are also medical conditions that can cause an eye muscle to be too tight or restricted, causing restrictive strabismus. If an eye is crossed inward toward the nose, esotropia exists. If an eye is turned toward the ear, it is called exotropia. If an eye is turned upward or downward, a hypertropia or hypotropia, respectively, exists.
Who Gets Strabismus?
In the preschool age group, three to five percent of children have some form of strabismus. The genetics or inheritance pattern of it is very complex and not completely understood. Overall, about 30 percent of patients with strabismus will have a close family relative.
Copyright 2009 NBC Health
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