Strabismus

Also called lazy eye, strabismus affects about one to three percent of children early in life. The condition develops when the two eyes are not fully coordinated, causing double vision. To compensate, the brain suppresses vision in one eye. Unless the condition is treated, vision in the suppressed eye will fail to develop normally, resulting in permanent visual impairment that may be mild or severe. If treated by the age of three, strabismus usually can be cured.

WHAT CAUSES STRABISMUS?
Strabismus has a strong hereditary component. The most common cause is an imbalance of muscle alignment: One eye crosses inward, upward or outward, while the other moves normally.

IS MEDICAL CARE NECESSARY?
Early detection is key to preventing permanent damage from strabismus; the condition does not readily respond to treatment after the age of six. Children from families with a history of strabismus (particularly in a sibling) should therefore be closely monitored.

WHEN SHOULD I SUSPECT THAT MY CHILD HAS STRABISMUS?
An infant's eyes will cross occasionally until about six weeks of age. If a baby cannot focus properly at that stage, your pediatrician may refer you to an ophthalmologist; the muscles controlling eye movement might be unbalanced or misaligned. Be sure to mention any concerns you have about your child's vision or eye movements to your pediatrician.

HOW CAN THE DOCTOR TELL IF MY CHILD HAS STRABISMUS?
To evaluate an infant, the doctor may move an attractive object or light through the field of vision to observe how the baby's eyes follow its movement. The doctor will probably test the two eyes separately, alternately covering each eye.

After diagnosing strabismus, the doctor will conduct more complete ophthalmological and neurological evaluations to rule out some serious eye or nervous system disease.

WHAT TREATMENTS ARE AVAILABLE?
The goal of therapy is to maximize vision in each eye and to obtain, if possible, equal and coordinated vision with normal depth perception. Treatment varies with the child's age, the type of strabismus involved and the degree of visual impairment. It may include the following:

• Patching the good eye to force the child to rely on the deviating eye and force the brain to pay attention to images received from the weaker eye

• Eyeglasses with one corrective lens and one blackened lens if the child has other vision problems (such as nearsightedness)

• Pharmacologic therapy with miotics, which contstrict the pupil. As a result, the weaker eye will respond to lower levels of nerve impulses and accommodate more readily. Because of side effects, this treatment is used only in selected cases.

• Orthoptics (eye exercises) as an adjunct to glasses, patching and medication

• Eye surgery to strengthen and coordinate muscles around the eyes in severe cases, usually before the age of one to two years

• Subsequent monitoring of the child's vision throughout childhood

GETTING HELP
Call your doctor if the following signs appear:

• Deviation in one eye, sometimes making the child appear crosseyed. Some children show such deviation only when they are ill or tired.

• Frequently head tilting or covering one eye to see an object up close

• Frequent headaches

• Difficulty estimating distances, which may show up as an inability to catch a ball

Excerpt from THE DISNEY ENCYCLOPEDIA OF BABY & CHILD CARE, © 1995 DSH Communications, Inc. This material is based on current medical research and, to the best of the editors' knowledge and understanding, is accurate and valid. However the reader should not use information contained in this material to alter a medically prescribed regimen or as a form of self-treatment, without seeking the advice of a licensed physician.