Strabismus refers to misaligned eyes. If the eyes turn inward (crossed), it is called esotropia. If the eyes turn outward (wall-eyed), it is called exotropia. One eye can be higher than the other, which is called hypertropia (for the higher eye) or hypotropia (for the lower eye). Strabismus can be subtle, (occurring occasionally), or constant. It can affect one eye only or shift between the eyes.
Strabismus usually begins in infancy or childhood, but many adults develop strabismus often due to trauma or brain tumors. Some toddlers have accommodative esotropia. Their eyes cross because they need glasses for farsightedness. Most cases of strabismus do not have a well-understood cause. It seems to develop because the eye muscles are uncoordinated and do not move the eyes together.
When young children develop strabismus, they typically have mild symptoms. They may hold their heads to one side if they can use their eyes together in that position. Or, they may close or cover one eye when it deviates. Often, the child’s brain learns to ignore or suppress the vision in the deviated eye. Adults, on the other hand, have more symptoms when they develop strabismus. They have double vision (see a second image) and may lose depth perception. Studies show school children with significant strabismus have self-image problems.
Amblyopia (Lazy Eye)
Amblyopia, or lazy eye, is closely related to strabismus. Children learn to suppress double vision so effectively that the deviating eye gradually loses vision. It may be necessary to patch the good eye and wear glasses before treating the strabismus. Amblyopia does not occur when the child alternates use of the deviated eyes. Adults do not develop amblyopia.
Strabismus is often treated by surgically adjusting the tension on the eye muscles. The goal of surgery is to straighten the eyes and allow them to move normally so that they will use the eyes together. Surgery is very successful at improving the condition, though a few patients (15-20%) will require additional surgery. Prisms and Botox® injections of the eye muscles are alternatives to surgery in some cases. Eye exercises are rarely effective.
The thought of having eye surgery can be frightening. To try to ease this experience, one of our physicians, Dr. George R. Beauchamp has developed the “Patient and Parent Guide to Strabismus Surgery”.