This research finding should lead to better compliance with treatment and improved quality of life for children with amblyopia, or "lazy eye," the most common cause of visual impairment in childhood. These results appear in the May issue of Archives of Ophthalmology.
"These results will change the way doctors treat moderate amblyopia and make an immediate difference in treatment compliance and the quality of life for children with this eye disorder," said Paul A. Sieving, M.D., Ph.D., director of the National Eye Institute, one of the Federal government‚s National Institutes of Health and the agency that sponsored the study. „This is very important, because it is estimated that as many as three percent of children in the U.S. have some degree of vision impairment due to amblyopia."
After four months of treatment, children with moderate amblyopia who wore an adhesive patch daily for two hours over their unaffected eye showed the same improvement in vision as those who wore a patch for six hours. Placing an opaque adhesive patch, or eye bandage, over the unaffected eye for six hours daily is considered one of the standard treatments for moderate amblyopia. Both groups of children in the study performed one hour a day of "near" work, such as coloring, tracing, reading, and crafts, while their eye was patched.
"This important study has yielded surprising results," says Scott Lambert, MD, pediatric ophthalmologist at Emory Eye Center and a principal investigator in the study. "While many would never have anticipated that patching for two hours would yield the same results as six hours, this study was conducted in a very careful manner and is, therefore quite credible. While the two-hour patching may not be applicable to every case, it will be sufficient for most patients, which is a very welcome outcome to both them and their parents."
"This commendable study also provides us with real scientific evidence about patching. In the past treatment was based on anecdotal information," he says.
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.
"Prior to these results, many children with amblyopia had to wear an eye patch during school hours," Dr. Sieving said. "For these children, the accompanying social and psychological stigma was very real. Many were stared at and teased by other children, which made them feel different. Now, children can look forward to attending school without the patch. This will make them feel better about themselves."
Dr. Sieving said it is crucial for young children to comply with the recommended treatment because visual impairment can persist into adulthood if amblyopia is not successfully treated in early childhood. Amblyopia is the most common cause of monocular (one eye) visual impairment among children and young and middle-aged adults.
"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," said study chairman Michael Repka, M.D., professor of ophthalmology and pediatrics at the Wilmer Eye Institute of Johns Hopkins University School of Medicine in Baltimore. „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."
Patching the unaffected eye has been the mainstay of amblyopia treatment for decades. In March 2002, the same researchers reported the effectiveness of a second treatment, which involved 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 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.
In this study, 189 children less than seven years old with moderate amblyopia were randomly assigned to receive either two hours or six hours of daily patching. The average age of the children was 5.2 years. Both groups showed significant improvement in the vision of the eye with amblyopia. "After four months, we found that 79 percent of children in the two-hour group and 76 percent of the patients in the six-hour group could read at least two more lines on the standard eye chart," Dr. Repka said. "The study also found that parents of children who wore the patch for six hours were more concerned about social stigma than the parents of children who wore the patch for two hours."
Dr. Repka said having the child perform one hour of "near," or close-up work per day while patched was an important part of the prescribed treatment. He said 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.
Dr. Repka noted that these results 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 in the Fall of 2003."
The study described in this release 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 and coordinated by the Jaeb Center for Health Research in Tampa, Florida.
Journal
Archives of Ophthalmology