Treatment improved the vision of many of the 507 older children with amblyopia studied at 49 eye centers. Previously, eye care professionals often thought that treating amblyopia in older children would be of little benefit. The study results, funded by the National Eye Institute (NEI), part of the National Institutes of Health (NIH), appear in the April issue of Archives of Ophthalmology.
“Doctors can now feel confident that traditional treatments for amblyopia will work for many older children, said Paul A. Sieving, M.D., Ph.D., director of the NEI. “This is important because it is estimated that as many as three percent of children in the United States have some degree of vision impairment due to amblyopia. Many of these children do not receive treatment while they are young,” he said.
Amblyopia is a leading cause of vision impairment in children and usually begins in infancy or childhood. It is a condition resulting in poor vision in an otherwise healthy eye due to unequal or abnormal visual input while the brain is developing in infancy and childhood. The most common causes of amblyopia are crossed or wandering eye (strabismus) or significant differences between the eyes in refractive error, such as, astigmatism, farsightedness, or nearsightedness.
Children in the study were divided randomly into two groups. One group was fitted with new prescription glasses only. The other group was fitted with glasses as well as an eye patch, or the eye patch along with special eye drops, to limit use of the unaffected eye. These children were also asked to perform near vision activities. The patching, near activities, and eye drops force a child to use the eye with amblyopia. Patching was prescribed for periods of two to six hours daily, while the eye drops were administered daily for the children seven though twelve years of age.
The study investigators defined successful vision improvement as the ability to read (with the eye with amblyopia) at least two more lines on a standard eye chart. The study investigators found that 53 percent of children age seven through twelve years who received both glasses and treatment with patches and near activity met this standard, while only 25 percent of those children in this age group who received glasses alone met the standard. For children age 13 through 17 years who were treated with both glasses and patches (these children did not get drops), 25 percent met the standard while 23 percent of children of these ages who received only glasses met the standard.
The study also revealed that among children age 13 through 17 years who had not been previously treated for amblyopia, 47 percent of those who were treated with glasses, patching and near activities improved two lines or more compared with only 20 percent of those treated with glasses alone. Despite the benefits of the treatment, most children, including those who responded to treatment, were left with some visual impairment. They did not obtain “20/20″ vision.
Rates of Success Treating Children With Amblyopia In Clinical Trial.*
Treatment Group ** Optical Correction Group (glasses only)
Ages seven through 12 53 percent 25 percent
Ages 13 through 17, no prior treatments 47 percent 20 percent
Ages 13 through 17 25 percent 23 percent
* The standard for success in the trial was a child’s ability to read at least two more lines on a standard eye chart using the eye with amblyopia. This may not be the maximum possible benefit that can be achieved with treatment.
** Treatment was eye patching, special eye drops, and near vision activities for ages seven through 12; eye patching and near activities for ages 13 through 17.
“This study shows how important it is to screen children of all ages for amblyopia.” said study co-chairman Richard W. Hertle, M.D., Children’s Hospital of Pittsburgh.
Commented co-chairman Mitchell M. Scheiman, O.D., Pennsylvania College of Optometry, “This study shows that age alone should not be used as a factor to decide whether or not to treat a child for amblyopia. The opportunity to treat amblyopia does not end with the pre-school years.”
It is not known, say the authors of the current study, whether vision improvement will be sustained in these children once treatment is discontinued. The NEI is supporting a one-year, follow-up study to determine the percentage of amblyopia that recurs among the children who responded well to treatment, as well as many other clinical studies of amblyopia at eye centers nationwide.
Dr. Sieving also commented that the current study results are “a wonderful example of the adaptability of the human visual system and brain. The NIH is exploring ways to take advantage of this adaptability in order to better understand and treat vision problems and other neurological conditions.”
The study described in this release was conducted by the NEI-funded Pediatric Eye Disease Investigator Group. The Group 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 coordinated by the Jaeb Center for Health Research in Tampa, Florida. A list of study centers is attached.
For background information regarding amblyopia, please visit www.nei.nih.gov/ats3/background.asp.
A list of current study centers is available online at www.nei.nih.gov/ats3/centers.asp.
The National Eye Institute is part of the National Institutes of Health (NIH) and is the Federal government’s lead agency for vision research that leads to sight-saving treatments and plays a key role in reducing visual impairment and blindness. The NIH is an agency of the U.S. Department of Health and Human Services.