What is Strabismus?

Strabismus, also known as crossed or turned eye, is the medical term used when the two eyes are not straight. It occurs in approximately 2 to 4 percent of the population.

What are the different types of strabismus?

There are three common types of strabismus:

  1. Crossed eyes. A child may be born with this condition, or it may develop within a few months of birth or around two years of age. This is also called esotropia, or convergent strabismus.
  2. Walleye, or divergent eyes. A child may be born with this condition, or it may develop later. This is also called exotropia, or divergent strabismus.
  3. Vertical strabismus. The eyes are out of alignment vertically.

What happens to sight in eyes with strabismus?

Defective binocular vision

The eyes need to be straight for fusion in the brain of the images of the two eyes. This gives accurate vision and stereopsis, or 3-D vision; 3-D vision is used to judge depth.

Reduction of vision in the turned eye (amblyopia)

A reduction of vision may occur in one eye in strabismus, especially under certain circumstances, such as late treatment.

One such circumstance is if a child is born with straight eyes, but one eye turns in around age two. If this condition is not treated urgently, vision may be reduced to partial sight (legal blindness) in the turned eye. If treatment is begun immediately, however, perfect vision can often be restored.