STRABISMUS

General Information

DEFINITION--Lack of coordinated muscle movement or focusing ability between the eyes, causing the eyes to point in different directions. One or both eyes may turn inward (crossed eyes) or outward ("walleye"). Eye alignment is not fully mature at birth. A true developmental eye drift typically shows up from birth to 3 or 4 months of age, but may occur in childhood or later.

BODY PARTS INVOLVED--Eyes; brain area that controls vision.

SEX OR AGE MOST AFFECTED--Both sexes; all ages.

SIGNS & SYMPTOMS

• Uncoordinated eye movements. This is sometimes evident only when looking in certain directions.
• Double vision (sometimes).
• Vision in one eye only, with loss of depth perception.

CAUSES--

In most cases, strabismus is congenital (present at birth) and the cause is unknown. Eye movement is controlled by brain signals to four muscles around each eye. Loss of coordinated movement results from:

• Muscle imbalance between the eyes.
• Lack of equal focusing ability in the eyes. The brain cannot tolerate differing focused images, so it ignores signals from one field of vision. The weaker eye eventually becomes useless from disuse, and a "lazy" or wandering eye results.
• Brain damage or head injury (rare).

RISK INCREASES WITH

• Family history of strabismus.
• Down syndrome
• Thyroid disease.
• Eye tumor.
• Damage to fetal central nervous system.
• Birth trauma.
• Eye disuse.

HOW TO PREVENT--No specific preventive measures.

What To Expect

DIAGNOSTIC MEASURES--

• Your own observation of symptoms. Note particularly if a young child covers one eye--this may indicate the eyes are not focusing together.
• Medical history and physical exam by a doctor, including tests of visual acuity, retina examination, total neurological exam and muscle tests.

> Treatment has 3 goals--

to obtain the best possible vision, gain the best eye alignment, provide the best opportunity for binocular vision.

• Treatment may include corrective glasses or an eye patch over the stronger eye to correct focusing imbalance (these force the weak eye to work), eye-muscle exercises, botulinum toxin (currently used only in adults) or surgery to correct the condition of the eye muscles. Sometimes a second operation is required. (See Strabismus Surgery in Surgery section.)
• Optional therapy involves the use of eye-glasses overlaid with thin plastic prisms. These are used by the patient prior to surgery and help determine the amount of surgical adjustment needed on the eye muscles.

POSSIBLE COMPLICATIONS

• Loss of normal vision in one eye.
• Psychological distress from an unattractive facial appearance.

PROBABLE OUTCOME--With early diagnosis, strabismus can be corrected with glasses, an eye patch, eye exercises or surgery. Without prompt treatment, vision loss in one eye may become permanent.

How To Treat

GENERAL MEASURES--

• Carefully follow your doctor's instructions about the use of eye patches. If you cover the good eye for too long a period, that eye may develop vision problems.
• Bandages are frequently unnecessary following surgery to correct strabismus. An antibiotic ointment is given to put in the child's eyes.

MEDICATION--Medicine usually is not necessary for this disorder unless botulinum toxin injections are recommended. They are injected into an eye-turning muscle, outside the eye, through an electromyographic needle.

ACTIVITY--No restrictions. Protect your child against falls or injury while he or she adjusts to an eye patch. No special diet.

Call Your Doctor If

Your child has symptoms of strabismus. Early diagnosis is vital to detect and treat underlying causes and prevent severe vision disability.