Researchers at the Johns Hopkins Children's Center and 34 other ophthalmology centers across North America report that in children with moderate amblyopia, or "lazy eye," patching the unaffected eye for two hours daily works just as well as patching the eye for six hours, the standard amblyopia treatment.
The findings, which appear in the May issue of the Archives of Ophthalmology, will likely change the way doctors treat moderate amblyopia and could lead to better compliance with treatment and improved quality of life for children with amblyopia, researchers say. The most common cause of visual impairment in childhood, amblyopia affects as many as 3 percent of children in the United States.
In the study, 189 children up to age 7, all with moderate amblyopia, were randomly assigned to wear an eye patch for two hours or six hours daily for four months. Both groups of children also performed one hour a day of "near" work, such as coloring, tracing, reading, and crafts, while their eye was patched. Children in both groups showed significant improvement in the vision of the eye with amblyopia, the researchers found.
"After four months, we found that 79 percent of children in the two-hour group and 76 percent of children in the six-hour group could read at least two more lines on the standard eye chart, a clear indication that wearing the patch for just two hours is an effective means of treatment," said study chairman Michael Repka, M.D., a pediatric ophthalmologist at the Children's Center and Wilmer Eye Institute at Johns Hopkins.
Repka noted that these findings do not necessarily apply to all children with amblyopia. "Children with more severe amblyopia, or who have amblyopia from causes other than crossed eyes or refractive error, may need a different treatment regimen," he said. "The Pediatric Eye Disease Investigator Group (PEDIG), which conducted this study, is currently conducting a clinical trial on children with severe amblyopia and expects the results will be available this fall."
"Because the daily burden to administer treatment for amblyopia falls on the parent, the findings from this study will immediately affect families that have young children with this eye disorder," he added. "The findings make it much easier for parents to monitor their children and encourage children to successfully comply with treatment. Timely and successful treatment for amblyopia in childhood can prevent lifelong visual impairment."
Having the child perform one hour of "near" work per day while wearing an eye patch was an important part of the prescribed treatment, Repka said. However, it remains unclear if the same amount of visual improvement would occur with patching alone. "We are planning a clinical trial to address the importance of near work in the treatment of amblyopia," he said.
Amblyopia, which usually begins in infancy or childhood, is a condition of poor vision in an otherwise healthy eye because the brain has learned to favor the other eye. Although the eye with amblyopia often looks normal, there is interference with normal visual processing that limits the development of a portion of the brain responsible for vision. The most common causes of amblyopia are crossed or wandering eyes or significant differences in refractive error, such as farsightedness or nearsightedness, between the two eyes. Without treatment compliance in early childhood, visual impairment can persist into adulthood.
Patching the unaffected eye has been the mainstay of amblyopia treatment for decades. In March 2002, Hopkins researchers also reported the effectiveness of a second treatment, using atropine eye drops that dilated the unaffected eye, temporarily blurring vision. Both treatments force the child to use the eye with amblyopia, stimulating vision improvement in that eye by helping the part of the brain that manages vision to develop more completely.
However, with patching, opinions among ophthalmologists varied widely on the number of daily hours it should be prescribed. No prior study had provided conclusive evidence of the optimal number of patching hours.
###This research was conducted by the PEDIG at 35 clinical sites throughout North America. The 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. The study was funded by the National Eye Institute, National Institutes of Health, and the U.S. Department of Health and Human Services.
For more information, please visit: http://www.nei.nih.gov/twovsix
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