Amblyopia, commonly known as lazy eye, is a condition in which there is blurry or reduced vision in one or both eyes that is correctable by glasses and/or contact lenses. Amblyopia causes more visual loss in children than all the injuries and diseases combined in this age group. Lazy eye causes loss of depth perception and reduced vision if not treated.
Amblyopia results from poor quality images being transmitted from the eye to the brain. The brain then shuts down (i.e. suppresses) the input from that eye, and neural connections in the part of the brain that provide small detail vision from that eye wither and die off.
Types of Amblyopia.
Strabismic amblyopia develops when one of the eyes are not straight. That eye may turn in, out, up or down which results in the brain favoring the eye that is straight and shutting off the eye that is turned.
Refractive amblyopia occurs when one eye has a higher refractive error than the other eye; the worse eye may be more farsighted or nearsighted, compared to the other eye. The brain will learn to adapt and start turning off the central vision from the eye that is sending a blurry image. With both eyes open, it may be difficult for parents and/or teachers to notice any visual problems since there is a functioning eye that is providing a clear image for the brain to see. This type of amblyopia in children may not be discovered until the child has a comprehensive eye exam. It is more common to see this in older school age children when the left eye is affected, because in vision screenings, usually the right eye is tested first and many children memorize the eye chart when they read it with the right eye and just repeat the answers with the poorly sighted left eye.
Deprivation amblyopia develops when congenital cataracts or other physical obstruction/conditions inhibit a child’s eye from properly developing – thus, depriving it of any visual stimulus. If not detected and treated early, children with one of these conditions can end up with very poor vision or, in extreme cases, lose vision. Depending on the condition, it can affect one or both eyes.
Treatment for Amblyopia.
Many doctors still think that there is a “critical period” or age beyond which a lazy eye cannot be corrected. This concept has been proven false, except for those who have experienced severe deprivation amblyopia. Neuroscience has established that the human brain is constantly changing, regardless of age. This phenomenon is known as “neuroplasticity.” Our oldest amblyopia patient began vision therapy at 72 years of age. At the age of 70, she lost the visual acuity in her “good” eye to a macular hole. Two years later, she was referred to our office. Through vision therapy she recovered enough visual acuity in the amblyopic eye to resume driving for another decade.
For those with deprivation amblyopia, there are higher success rates if the obstruction is detected and removed early in life. A combination of patching (usually 2-4 hours/day) and programmed vision therapy exercises performed on a daily basis for 30 to 45 minutes during that patching time is sufficient to make marked improvements in visual acuity in an amblyopic eye. Patients ordinarily do not have to wear a patch at work or school. The treatment regimen depends each patient’s specific diagnosis, and while improvement will be generally be seen within one or two months, it may take six to 12 months or more to achieve maximal results.