Amblyopia

Causes

What causes amblyopia?

Amblyopia can be caused by a number of conditions, including:

• Strabismus: Strabismic amblyopia is caused by misalignment of the eyes. The brain ignores the signals sent from the eye that is not straight.

• Refractive Error: Refractive amblyopia can be caused by a condition called anisometropia. This occurs when the glasses prescription between the eyes is different, and one eye has more nearsightedness, farsightedness or astigmatism than the other. The brain “turns off” the eye with the worse prescription and blurrier image. Refractive amblyopia may also occur in both eyes if the glasses prescription is high but equal in each eye.

• Deprivation: Deprivation amblyopia can be caused by any condition that blocks (“deprives”) the vision in your child’s eyes, such as cataracts, ptosis (drooping eyelids) or a hemangioma.

How common is amblyopia?
As many as 4 percent of children have amblyopia. It is the most common cause of vision loss in childhood, yet it is almost always treatable if detected early.

Symptoms

What are the symptoms of amblyopia?

Symptoms are related to the condition causing your child’s amblyopia.

• Strabismic amblyopia: One or both of your child’s eyes will turn inward, outward, upward or downward.

• Refractive amblyopia: Unfortunately, there may not be any symptoms of amblyopia caused by anisometropia. Your child may not appear to have any vision problems since he or she is depending on the normal, good eye, which is what makes this variety of amblyopia so difficult to diagnose. If your child has bilateral refractive amblyopia, your child may move close to objects, squint or turn his or her head to see.

• Deprivation amblyopia: Your child will have the symptoms of cataracts, ptosis (drooping eyelids), hemangioma or other underlying condition that is blocking the vision.

What if amblyopia isn’t diagnosed and treated early?

By the time a child is between 8 and 12 years old, it can be difficult to reverse the vision loss from amblyopia. Researchers are constantly working to invent new ways of diagnosing amblyopia earlier in a child's life so the disease can be treated more effectively. The Pediatric Vision Scanner, developed at Boston Children’s and currently in trials, is a simple screening test that has proven quite effective in identifying amblyopia in young children.

What is the long-term outlook for my child?

It depends upon the underlying cause of your child’s amblyopia, but what is true in all cases is that the sooner the condition is diagnosed, the more effective the treatment will be.