Amblyopia, or "lazy eye," is the loss of one eye's ability to see details. It is the most common cause of vision problems in children.

Amblyopia occurs when the brain and eyes do not work together properly. In persons with amblyopia, the brain favors one eye.

The preferred eye has normal vision, but because the brain ignores the other eye, a person's vision ability does not develop normally. Between ages 5 and 10, the brain stops growing and the condition becomes permanent.

Strabismus is the most common cause of amblyopia, and there is often a family history of this condition.

Other causes include:

• Astigmatism in both eyes
• Childhood cataracts
• Farsightedness
• Nearsightedness

• Eyes that turn in or out
• Eyes that do not appear to work together
• Inability to judge depth correctly

Amblyopia is usually easily diagnosed with a complete examination of the eyes. Special tests are usually not required.

The main treatment involves patching the normal eye to force use of the lazy eye. Sometimes, drops are used to blur the vision of the normal eye instead of putting a patch on it.

The underlying condition will also require treatment. If the lazy eye is due to a vision problem (nearsightedness or farsightedness), glasses or contact lenses will be prescribed.

For treatment of crossed eyes, see: Strabismus

Children whose vision cannot be expected to fully recover should wear glasses with protective lenses of polycarbonate, as should all children with only one good eye caused by any disorder. Polycarbonate glasses are shatter- and scratch-resistant.

Children who receive treatment before age 5 usually have a near complete recovery of normal vision.

Delaying treatment can result in permanent vision problems. After age 10, only a partial recovery of vision can be expected.

• Eye muscle problems that may require several surgeries, which can have complications
• Permanent vision loss in the affected eye

Call for an appointment with your health care provider or ophthalmologist if a vision problem is suspected in a young child.

Early recognition and treatment of the problem in children can help to prevent permanent visual loss. All children should have a complete eye examination at least once between ages 3 and 5.

Olitsky SE, Hug D, Smith LP. Disorders of the Uveal Tract. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 628.

Doshi NR. Amblyopia. Am Fam Physician. Feb. 2007; 75(3): 361.