Amblyopia (am-blee-o-pee-ah) is an eye condition that is sometimes called lazy eye. Amblyopia is the result of an eye and the brain not working properly together. Amblyopia affects more people in the first four decades of life than ocular injury and ocular diseases combined.

Amblyopia can be described as a loss of clarity or sharpness of vision in one eye. As a result, vision remains below normal despite optimum eyeglass correction. There are three main causes or types of amblyopia:
Refractive amblyopia: This common cause of amblyopia occurs when one eye has a significant difference in visual error (nearsightedness, farsightedness, or astigmatism) than the other eye. Since the brain controls vision, if one eye has better vision than the other, it makes visual judgments utilizing the better eye.
Strabismic amblyopia: This is another common cause of amblyopia. It occurs when there is an inability to use both eyes together as a team resulting in a crossed eye (strabismus). In this case, one eye may veer in or out causing double vision. To avoid confusion, the brain only pays attention to one eye.
Deprivation amblyopia: This is a less common cause of amblyopia. It occurs if a child is born with a cataract, a severe droopy eyelid, an abnormality to the front surface of the eye (the cornea), a severely underdeveloped eye, or in rare cases, an extremely high fever during early childhood.

The successful treatment of amblyopia is highly dependent on the age of the patient. The younger the child, the better prognosis for recovering vision. If eyeglasses are prescribed and if vision remains decreased, eye patching is generally used in trying to improve vision. The success of eye patching depends on the age of detection, the extent of the amblyopia, and the cooperation of the patient. With this technique, the eye with the better vision is patched so that the eye with less vision will be used.
As a general rule, eye patching has little benefit after the visual system matures (about age 12). Once the visual system matures, the vision we have established will stay at the level throughout our lifetime unless a secondary disease process occurs.