What is amblyopia?

Amblyopia is poor vision in an eye that did not develop normal sight during early childhood. It is sometimes called lazy eye. When one eye develops good vision while the other does not, the eye with poorer vision is called amblyopic. Usually, only one eye is affected by amblyopia. The condition is common, affecting approximately 2 or 3 out of every 100 people. The best time to correct amblyopia is during infancy or early childhood.

When should vision be tested?

It is recommended that all children have their vision checked by their pediatrician, family physician or ophthalmologist (medical eye doctor) at or before their fourth birthday.

What causes amblyopia?

Amblyopia is caused by any condition that affects normal use of the eyes and visual development. In many cases, the conditions associated with amblyopia may be inherited. Children in a family with a history of amblyopia or misaligned eyes should be checked by an ophthalmologist early in life.

How is amblyopia diagnosed?

It is not easy to recognize amblyopia. A child may not be aware of having one strong eye and one weak eye. Unless the child has a misaligned eye or other obvious abnormality, there is often no way for parents to tell that something is wrong. Amblyopia is detected by finding a difference in vision between the two eyes. Since it is difficult to measure vision in young children, your ophthalmologist often estimates visual acuity by watching how well a baby follows objects with one eye when the other eye is covered. Using a variety of tests, the ophthalmologist observes the reactions of the baby when one eye is covered. If one eye is amblyopic and the good eye is covered, the baby may attempt to look around the patch, try to pull it off or cry.

Poor vision in one eye does not always mean that a child has amblyopia. Vision can often be improved by prescribing glasses for a child.

Your ophthalmologist will also carefully examine the interior of the eye to see if other eye diseases may be causing decreased vision. These diseases include:

• Cataracts
• Inflammations
• Tumors
• Other disorders of the inner eye
  

How is amblyopia treated?

To correct amblyopia, a child must be made to use the weak eye. This is usually done by patching or covering the strong eye, often for weeks or months. Even after vision has been restored in the weak eye, part-time patching may be required over a period of years to maintain the improvement. Glasses may be prescribed to correct errors in focusing. If glasses alone do not improve vision, then patching is necessary. Occasionally, amblyopia is treated by blurring the vision in the good eye with special eye drops or lenses to force the child to use the amblyopic eye. Amblyopia is usually treated before surgery to correct misaligned eyes, and patching is often continued after surgery as well.