Amblyopia, or lazy eye, is a fairly common eye problem (affecting about 2 out of 100 children) that develops when a child has one eye that doesn’t see well or is injured, and he begins to use the other eye almost exclusively.
The idle eye then relaxes and becomes even weaker. In general, the problem must be detected by the age of three in order to treat and restore normal vision in the affected eye by age six. If this situation persists for too long (past seven to nine years of age), vision may be lost permanently in the unused eye.
Once an ophthalmologist diagnoses the problems in the unused eye, your child may need to wear a patch over the “good” eye for periods of time. This forces her to use and strengthen the eye that has become “lazy.” Patching therapy will be continued for as long as necessary to bring the weaker eye up to its full potential.
This could take weeks, months, or even up to age ten or older. As an alternative to the patch, the ophthalmologist might prescribe eye drops or ointment to blur the vision in the good eye, thereby forcing your child to use the amblyopic eye.