Amblyopia, also known as “lazy eye,” is the loss in one eye of the ability to see details. The brain and the eyes work together to produce vision. Amblyopia occurs when the vision of one eye is reduced because it fails to work properly with the brain. The eye itself looks normal, but for various reasons the brain favors the other eye. This condition is the most common cause of visual impairment in children, affecting 2 to 3 out of every 100 children. Unless it is successfully treated in early childhood, it can cause permanent visual impairment in adults.
Amblyopia may also result from treatable conditions that prevent the eye from focusing clearly, including strabismus – the misalignment of the two eyes either inward or outward. A common cause is the inability of one eye to focus as well as the other one, especially when one eye is more nearsighted or more farsighted, or has more astigmatism than the other. Occasionally, amblyopia is caused by clouding of the front part of the eye, a condition called a cataract. The end result of all types of amblyopia is reduced vision in the affected eye. Amblyopia may also occur in both eyes.
Amblyopia is diagnosed through a careful history and thorough vision screening by a pediatric ophthalmologist. Vision screening is particularly important because the condition often goes undiagnosed unless the child shows asymmetric visual behavior or acuity. Symptoms include eyes that turn in or out, eyes that do not appear to work together, inability to judge depth accurately or poor vision in one eye. Tests may include age-appropriate visual acuity testing, testing of binocular vision and ocular alignment.
In cases of nearsightedness, farsightedness and astigmatism, consistent use of glasses may help correct amblyopia. Children can wear glasses or contact lenses from the age of one week. Because the brain is accustomed to seeing a blurry image with the affected eye, glasses alone do not improve vision to 20/20.
The two most common ways to treat amblyopia are patching and eye drops. Your pediatric ophthalmologist may recommend wearing an adhesive patch over the stronger eye for a few hours daily for a period weeks or months to force the child to use the weaker eye. Patching stimulates vision in the weaker eye and helps parts of the brain involved in vision develop more completely. When drug therapy is used, a drop of a drug called atropine is placed in the stronger eye to temporarily blur vision so that the child will use the eye with amblyopia, especially when focusing on near objects. Research studies have shown both methods of treatment to be effective.
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