Strabismus

What is Strabismus?

Strabismus, commonly known as squint, is a visual defect in which the eyes are misaligned and point in different directions. One eye may look straight ahead, while the other eye may turn inward, outward, upward and downward.

You may find that the misalignment is a constant feature, or it may come and go. The turned eye may straighten at times and the straight eye may turn.
Strabismus is common among children. About 4% of all children in the United States have strabismus. It can also occur later in life.

In occurs equally in males and females. Strabismus may run in families. However, many people with strabismus have no relatives with the problem.

Amblyopia

Good vision develops during childhood when both eyes are normally aligned. Strabismus may cause reduced vision, or amblyopia, in the weaker eye. The brain will recognize the image of the better-seeing eye and ignore the image of the weaker or amblyopic eye. This occurs in approximately half the children who have strabismus.

Amblyopia can be treated by patching the "good" eye to strengthen and improve vision in the weaker eye. If amblyopia is detected in the first few years of life, treatment is usually successful. If treatment is delayed, amblyopia can become permanent. As a rule, the earlier it is treated, the better the chances of saving vision.

What causes Strabismus?

The exact cause of strabismus is not fully understood. Six eye muscles, controlling the eye movement, are attached to the outside of each eye. In each eye, two muscles move the eye right or left. The other four muscles move it up or down and at an angle.

To line up and focus both eyes on a single target, all the muscles in each eye must be balanced and working together. In order for the eyes to move together, the muscles in both eyes must coordinated.

The brain controls the eye muscles. Strabismus is especially common among children with disorders that affect the brain, such as 
Cerebral palsy, Down syndrome, Hydrocephalus, and Brain tumors.

A cataract or eye injury that affects the vision can also cause strabismus.

What are the symptoms of Strabismus?

The main symptom is an eye that is not straight. Sometimes children will squint with one eye in bright sunlight or tilt their head to use their eyes together.

How is strabismus diagnosed?

Strabismus can be diagnosed during an eye examination. It is recommended that all children have their vision checked by their pediatrician, family doctor or ophthalmologist on or before their fourth birthday. If there is a family history of strabismus or amblyopia, an ophthalmologist can check the vision even before the age of three.

An infant's eyes may seem to be crossed. Young children often have a wide, flat nose and a fold of skin at the inner eyelid that can make the eyes appear crossed. This appearance of strabismus may reduce as the child grows. A child will not outgrow true strabismus.

An ophthalmologist can usually tell the difference between true and false strabismus.