Amblyopia- “Lazy Eye”
Amblyopia, or “lazy eye” is the lack of central vision in an eye that is not correctable with a lens or due to any health problem. It generally occurs before six years of age and does not affect peripheral vision. Usually only one eye is affected, but on occasion both are. This condition is often due to the eyes not being used together and can be associated with crossed-eyes or an extreme difference in visual acuity between the eyes. This vision impairment may become permanent since as the brain matures it learns to ignore the images coming from the affected eye.
There are three different causes: stabismic, deprivation, and refractive. Strabismic amblyopia is due to the misalignment of the eyes such as an eye turning in or out. This can cause “double vision” and results in the brain learning to discard that information in an effort to correct the image. Deprivation amblyopia is caused by a congenital cataract or other opacity blocking light in the eye and impeding vision. Refractive amblyopia occurs when there is an extreme difference in visual acuity between the eyes. This difference could be related to nearsightedness, farsightedness, or astigmatism.
Symptoms of lazy eye may include bumping into things on one side in particular or favoring one of the eyes. The eye may wander inward or outward and it may be readily apparent that they are not working together. On occasion wandering eyes can be the first symptom of an eye tumor, so it is imperative to see your optometrist if this is ever noticed.
The symptoms of amblyopia may go undetected due to their subtle nature. Many people with mild amblyopia aren’t even aware that there is a problem since the vision in their better eye is normal. Individuals with severe amblyopia have reported poor depth perception, poor spatial acuity, low sensitivity to contrast, and reduced sensitivity to motion. Many of these children are missed on school screenings and pediatric visual acuity testing. Therefore, it is important to have all children examined by a pediatric ophthalmologist or optometrist by the age 6 months, then again by 3. We recommend annual eye exams for all school age children as well.
Treatments for amblyopia may include a combination of techniques like eye patching, prescription lenses, eye drops, prisms and vision therapy. In vision therapy the individual with the eye turn learns to use both eyes together in an effort to prevent lazy eye from developing.
Early treatment is vital in order to increase the likelihood of complete recovery. It is recommended that children have full eye exams at six months and again at three years. Doctors examine children’s ability to see equally well with both eyes, check to see if both eyes move together, and verify that light reaches the back of their eyes correctly. Lazy eye will not resolve on its own and a late diagnosis increases the duration of treatment and is often less effective. These individuals often have less than 20/200 vision in the affected eye as an adult.