Strabismus can be categorized by the direction of the turned or misaligned eye:
Inward turning (esotropia)
Outward turning (exotropia)
Upward turning (hypertropia)
Downward turning (hypotropia)
It may be of 3 sub types
1. Converge - When the eye turn in
2. Diverge - when eye turn out.
3. Sometimes turn up or down, preventing the eyes from working properly together.
There are several forms of strabismus.
The two most common clinical are:
Accommodative esotropia: This often occurs in cases of uncorrected farsightedness and a genetic predisposition (family history) for the eyes to turn in. Because the ability to focus is linked to where the eyes are pointing, the extra focusing effort needed to keep distant objects in clear focus may cause the eyes to turn inward. Symptoms include double vision, closing or covering one eye when looking at something near, and tilting or turning the head. This type of strabismus typically starts in the first few years of life. This condition is usually treated with glasses, but may also require eye patching and/or surgery on the muscles of one or both eyes.
Intermittent exotropia: In this type of strabismus, one eye will fixate (concentrate) on a target while the other eye is pointing outward. Symptoms may include double vision, headaches, difficulty reading, eyestrain, and closing one eye when viewing far away objects or when in bright light. Patients may have no symptoms while the ocular deviation (difference) may be noticed by others. Intermittent exotropia can happen at any age. Treatment may involve glasses, patching, eye exercises and/or surgery on the muscles of one or both eyes.
Another type of strabismus is called infantile esotropia. This condition is marked by a large amount of inward turning of both eyes in infants that typically starts before six months of age. There is usually no significant amount of farsightedness present and glasses do not correct the crossing. Inward turning may start on an irregular basis, but soon becomes constant in nature. It is present when the child is looking far away and up close. The treatment for this type of strabismus is surgery on the muscles of one or both eyes to correct the alignment.
Adults can also experience strabismus. Most commonly, ocular misalignment in adults is due to stroke, but it can also occur from physical trauma or from a childhood strabismus that was not previously treated or has recurred or progressed. Strabismus in adults can be treated in a variety of ways, including observation, patching, prism glasses and/or strabismus surgery.