Amblyopia Facts & Prognosis

Overview

Amblyopia, sometimes called “lazy eye,” occurs when an abnormal relationship between the visual input from one eye and its interpretation in the brain diminishes vision. In “Amblyopia Facts,” the National Eye Institute says amblyopia affects 2 to 3 percent of children, making it the most common cause of impaired vision in childhood.

Causes

Amblyopia results from any impairment that compromises the visual system or its input to the brain. Cataracts, which are a clouding of the lenses, abnormal eye structure, severe astigmatism and a severe mismatch in the degree of near- or far-sightedness between the eyes all can cause amblyopia, but the most common cause is strabismus–weak eye muscles that allow an eye to drift out of alignment.

Treatments

Amblyopia treatments correct any underlying “refractive” problems such as astigmatism or near- or far-sightedness with glasses, and then attempt to strengthen and reinforce the connections between the weak eye and the brain by limiting the input from the stronger eye. The stronger eye can be physically covered with a patch for several hours a day, or atropine eyedrops can temporarily block its input, forcing the brain to rely on input only from the weaker eye.

Prognosis-Young Children

The primary connections between the eye and the brain fully form in the first 6 to 9 years of life, according to the National Eye Institute, so amblyopia treatments are most successful when applied to young children. Within weeks to months of treatment with patching or atropine eyedrops in children about 7 years old or younger, vision in the weaker eye begins to improve, says the Mayo Clinic.

Prognosis-Older Children

Eye doctors used to believe that treatment could not help children older than about 7 who suffered from amblyopia. However, results from studies sponsored by the National Eye Institute in 2005 refute that belief. Fifty-three percent of children 7 to 12 years old age who had corrective lenses and treatment for amblyopia significantly improved their performance on a standard vision test, compared to only 25 percent of those given only corrective lenses. Overall, children 13 to 17 did not improve as much with treatment, but of those who had never been treated for amblyopia before, 47 percent showed significant improvement in vision. Despite significant improvement, most children did not have perfect “20/20” vision after treatment.

Prognosis-Adults

Amblyopia is the most common reason for visual impairment in one eye in young and middle-aged adults, according to the National Eye Institute. The results for treatment in older children leave hope that some adults with amblyopia could benefit from treatment as well. However, the institute says that while scientists are performing studies to gauge the effectiveness of amblyopia treatment in adults, the results are limited and inconclusive so far.

About this Author

In 20 years as a biologist, Susan T. McClure has contributed articles to scientific journals such as “Nature Genetics” and “American Journal of Physiology.” She earned her Ph.D. from the University of Maryland. She enjoys educating people about science and the challenge of making complex information accessible.