Amblyopia, a condition that involves poor vision and/or poor muscle control of one eye, has been effectively treated in children younger than six for some time, but it generally has been believed that older children would be unlikely to benefit from treatment, according to background information in the article.

The upper limit for successful treatment response has been believed to be six to seven, or nine to ten years of age. The current study is designed to evaluate the effectiveness of treatment of amblyopia in children aged seven to 17 years.

Patching, Near-Visual Activities, Atropine

Mitchell M. Scheiman, O.D., Richard W. Hertle, M.D., and colleagues in the Pediatric Eye Disease Investigator Group (PEDIG), conducted a randomized treatment trial of 507 older children with amblyopia at 49 clinical sites.

All the patients were provided with optimal optical correction (children who already had glasses were given new ones). Children were then randomly assigned to receive treatment for amblyopia or to receive optical correction alone.

Children aged seven to 12 in the treatment group were treated with two to six hours a day of patching over the sound eye combined with near visual activities, such as playing with a GameBoy, homework or reading, and one drop daily of atropine for the sound eye.

Patients in the older treatment group (aged 13 to 17 years) were treated with patching and near visual activities alone.

Follow up visits occurred every six weeks for up to 24 weeks until the patients were classified as a responder or non-responder.

A patient in the study was classified as a responder if the amblyopic eye acuity (sharpness of vision) was 10 or more letters (two lines on the eye chart) better than baseline. A patient was classified as a non-responder if amblyopic eye acuity had not improved 10 or more letters by the 24th week or if there was no improvement at all from a prior follow-up visit (or baseline).

Acuity Can Be Improved in Older Kids

Of the 404 seven- to 12-year-olds in the study, 53 percent (106 of 201) in the treatment group were responders compared with 25 percent in the optical correction group.

Of the 13- to 17- year-olds, 25 percent of the treatment group (14 of 55) were responders compared with 23 percent of the optical correction group (11 of 48).

However, of the 13- to 17- year-olds who previously had not been treated for amblyopia, 47 percent (eight of 17) responded to treatment compared to 20 percent (four of 20) who did not.

“Although our results indicate that visual acuity can be improved by treating amblyopia in older children, it is not known whether the improvement will be sustained after treatment is discontinued,” the authors write. “Therefore, a conclusion regarding the long-term benefit of treatment and the development of treatment recommendations for amblyopia in children seven years and older will need to await the results of a follow-up study we are conducting on the patients who responded to treatment.”

Early Treatment Is Best

“The results indicate that visual acuity may improve modestly in some cases, says David G. Hunter, M.D., Ph.D., of Harvard Medical School, Boston, in an editorial accompanying this study.

"Surprisingly, vision improved in many patients treated with optical correction alone …. The response could perhaps have been better, but the treatment chosen for older patients was minimal. Sixty-two percent of older patients in the treatment group were prescribed only two hours of patching, without atropine, despite a lack of published evidence that such limited treatment might be effective in severe amblyopia,” Dr. Hunter noted.

“Until we know the regression rate in these age groups (which may be very high) and the functional benefits of a two-line (10-letter) improvement in visual acuity at this age (which may be minimal), we will not know whether there is reason to treat older amblyopia patients,” Dr. Hunter continues.

“Until we know whether to treat, we will not know whether to screen populations for amblyopia at this age. Thus, although the study unearthed much new information about amblyopia in older children, the authors do not make any recommendations about treatment of these patients, nor should they until they obtain follow-up results,” he cautions.

“In this study, some older patients with amblyopia responded to treatment, but most did not,” Dr. Hunter points out.

“Those who did respond were left with a residual visual acuity deficit. The take-home lesson is that considering how difficult it is to treat older children for amblyopia, it is vitally important to identify and treat amblyopia early in life, well before age seven years," he urges.

"This can be achieved by (1) increasing awareness (in parents and primary care providers) that amblyopia is a silent threat to vision, (2) improving our ability to screen children for amblyopia in the preschool years, and (3) ensuring that patients, once identified, will have access to care. If these goals can be achieved, the question of whether or how to treat older patients with severe amblyopia will become a strictly academic pursuit,” Dr. Hunter concludes.