Amblyopia (lazy eye) is the loss or lack of development of vision in an eye that is unrelated to any eye health problem. The brain, for some reason, does not acknowledge the images seen by the amblyopic eye. Reduced vision due to amblyopia is not correctable with lenses alone.
Amblyopia is generally the result of poor early visual development, and as such, usually occurs before the age of eight. Infants born prematurely or with low birth weight are at a greater risk for the development of the condition.
It is estimated that two to four percent of children have amblyopia. The chance of amblyopia developing during adulthood is very small.
Amblyopia usually results from a failure to use both eyes together. It can be caused by the presence of strabismus (crossed-eyes), unequal refractive error (farsightedness or nearsightedness), or a physical obstruction of vision (cataract).
If there is a large enough difference in the degree of nearsightedness, farsightedness or astigmatism between the two eyes, or if the eyes are crossed, the brain learns to ignore one image in favor of the other.
Normally, the images sent by each eye to the brain are identical. When they differ too much, the brain learns to ignore the poor image sent by one eye and "sees" only with the good eye.
The vision of the eye that is ignored becomes weaker from disuse.
The amblyopic eye is never blind in the sense of being entirely without sight.
Amblyopia affects only the central vision of the affected eye. Peripheral awareness will remain the same.
Amblyopia usually produces few symptoms. It may be accompanied by crossed-eyes or a large difference in the refractive error between the two eyes. A child may also exhibit noticeable favoring of one eye and may have a tendency to bump into objects on one side.
A comprehensive optometric examination can determine the presence of amblyopia. The earlier it is diagnosed, the greater the chance for a successful treatment.
Since amblyopia occurs only in one eye, the good eye takes over and the individual is generally unaware of the condition. That is why it is important to have your child's vision examined at about six months, at age three and again before he or she enters school.
Corrective lenses, prisms and/or contact lenses are often used to treat amblyopia.
Covering or occluding the better eye, either part-time or full-time, may be used to stimulate vision in the amblyopic eye. In addition, a program of vision therapy may be prescribed to help improve vision function.
Vision in the amblyopic eye may continue to decrease if left untreated. The brain simply pays less and less attention to the images sent by the amblyopic eye. Eventually, the condition stabilizes and the eye becomes virtually unused. It is quite difficult to effectively treat amblyopia at this point.
Early detection and treatment of amblyopia and significantly unequal refractive errors can help to reduce the chances of one eye becoming amblyopic.