What is strabismus? Strabismus is an eye condition commonly called crossed eyes. It occurs when the eyes are not properly aligned and point in different directions. Since the two eyes cannot look at the same point at the same time, the images the two eyes send to the brain do not match. A child may, at first, register this as double vision (diplopia), but since the child's brain cannot process the two different images, it begins to ignore whichever eye has weaker vision. And when this one eye is not used over time, it may become what is called a "lazy eye" (amblyopia).
What causes strabismus? Many cases of strabismus are considered congenital - present at birth - or infantile - developing within the first 6 months after birth. Most strabismus is due to the improper coordination of the 6 muscles of the eyes or to refractive errors (vision in one eye is worse than the other, due to nearsightedness, farsightedness, or astigmatism). More rarely, crossed eyes may be caused by retinoblastoma, cataracts, or other eye or neurological diseases. Strabismus can also develop later in life as a complication of diabetes, or as a result of a brain tumour, head trauma, neurologic condition, viral infection (meningitis), eye injury, infection, or other problem.
What are the risk factors for strabismus? About 3 out of every 100 children have strabismus, with first symptoms occurring between birth and 21 months of age. The risk increases if there is a family history of crossed eyes or if a child is born prematurely, has low birth weight, or is exposed to drugs or alcohol before birth.
What are the signs and symptoms of strabismus? The most obvious symptom of strabismus is eyes that appear crossed or that do not seem to move in the same directions. Sometimes what looks like crossed eyes is actually pseudostrabismus: A child may have a wide flat nose and a fold of skin at the inner eyelid that makes it appear that eyes are crossed. An eye affected by true strabismus will not only look crossed but will tend to turn up or down or wander in a direction opposite from the other eye. Children with strabismus may also squint one eye while in bright light or tilt their head to try to correct their vision. Difficulties at school may be an indication of vision problems as well. An adult who develops strabismus may have double vision. A child generally does not have double vision because their brain has learned to ignore the image coming from the turned eye.
Will my child outgrow strabismus? Strabismus cannot be outgrown. In fact, without treatment the condition may worsen and lead to lazy eye (amblyopia) and/orpermanent vision loss. Children with strabismus or amblyopia need treatment to correct the imbalances and prevent future vision problems.
What should I do if I think my child has strabismus? If you suspect that your child's eyes are affected by strabismus, make an appointment with your family doctor or eye doctor. Early detection and treatment can correct strabismus.
How is strabismus treated? In some cases of strabismus, eyeglasses may be prescribed to help straighten the eyes. If amblyopia (lazy eye) has developed, patching the stronger eye can help to strengthen and straighten the weaker eye. Surgery is sometimes necessary in order to adjust unbalanced eye muscles or if a cataract impairs vision. Eye exercises or vision therapy may also be recommended by the doctor to strengthen or straighten eye muscles.