Researchers at the Johns Hopkins Children's Center and 48 eye centers across North America report that many children between the ages of 7 and 17 with amblyopia, or "lazy eye," may benefit from treatments usually prescribed for younger children.
"Previously, many eye specialists thought treating amblyopia in older children would be ineffective, but we found that many teenagers responded to treatment," says Michael Repka, M.D., a pediatric ophthalmologist at the Children's Center and a co-author of the study.
"In our opinion, age alone should not determine whether or not to treat." The findings are published in the April issue of the Archives of Ophthalmology.
Amblyopia is the most common cause of visual loss in childhood, affecting as many as 3 percent of children in the United States. With onset in infancy or childhood, the condition is marked by poor vision in an otherwise healthy eye and occurs because the brain has learned to favor the other eye. Although the amblyopic eye often looks normal, abnormal visual processing limits the development of a portion of the brain responsible for sight. The most common causes are crossed or wandering eyes, farsightedness or nearsightedness.
In the study, 507 children were randomly divided into two groups. One was fitted with new prescription eyeglasses only; the other was fitted with glasses with a plain eye patch or an eye patch with atropine eyedrops covering the healthy eye. Patching was prescribed for periods of two to six hours daily, while the eyedrops were administered daily for children. Children wearing patches or receiving eyedrops were also asked to perform near-vision activities, such as drawing or reading.
In the study, 53 percent of children ages 7 through 12 with glasses, patch treatment and near-vision activity could, after 24 weeks, read at least two more lines on a standard eye chart, which the researchers defined as successful vision improvement. A fourth of children in this age group using glasses alone also met this standard.
For children ages 13 through 17 treated with glasses and eye patches (no drops were given to them), 25 percent experienced vision improvement, compared to 23 percent with glasses only.
Almost half of the children ages 13 to 17 who had not been previously treated for amblyopia improved after being treated with glasses and eye patches, while 20 percent of children treated with glasses alone responded to treatment.
Despite the benefits of treatment, most children - including those who responded to treatment - were left with some visual impairment and did not obtain "20/20" vision. Repka says it is also not known whether vision improvement will be sustained in these children once treatment is discontinued. A follow-up study is planned to determine the percentage of amblyopia that recurs among the children who responded well to treatment.
This research was conducted by the Pediatric Eye Disease Investigator Group (PEDIG) at 49 clinical sites throughout North America and was funded by the National Eye Institute and National Institutes of Health. PEDIG focuses on studies of childhood eye disorders that can be implemented by both university-based and community-based practitioners as part of their routine practice.