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The Pediatric Eye Disease Investigator Group has conducted several studies recently that are helping to clarify the effectiveness of various approaches to amblyopia treatment and evaluate the effectiveness of therapies in different age groups.
Dr. Wallace began his summary with an evaluation of how well glasses alone treat amblyopia. The objective of this study was to determine the incidence of successful treatment of previously untreated anisometropic amblyopia with spectacles alone. The study enrolled 180 children aged 3 to 7 years; visual acuity in the amblyopic eye was in a range of 20/40 to 20/400 with at least three lines of interocular difference. Amblyopia was secondary to strabismus or anisometropia or both.
In this two-phase trial, Amblyopia Treatment Study 5 (ATS 5), children were first prescribed spectacles or given an updated spectacle prescription at a screening visit. During the spectacle phase of the study, they were followed every 5 weeks until the amblyopia resolved or no further improvement occurred. This phase included 84 children at 34 sites; their mean age was 5.2 years. The mean baseline amblyopic eye acuity was about 20/80.
Because the children were followed until improvement stopped, investigators also were able to measure best visual acuity achieved with glasses at any visit, Dr. Wallace added. The mean improvement for the cohort was about three lines.
Amblyopia resolved in 27% of the patients with glasses alone, he said, and the condition continued to improve and resolve in some additional patients while they were in the control arm during the randomized portion of the trial.
"There are certainly some advantages to amblyopia treatment with spectacles alone," Dr. Wallace said.
"A lot of these patients don't need atropine or patching at all, so we save them that treatment. And if patching is needed, there may be better visual acuity when patching is started in many cases. The child may be more likely to comply with patching if it's started when visual acuity is 20/50 compared with 20/100."
Also, he said, "I like the idea of initiating one new treatment at a time," rather than fitting children with glasses and asking them to undergo patching as well. A nice approach is for parents to encourage their children to be adherent with glasses-wearing and then wait for a reasonable period to see how well they do before considering other treatment approaches, he said.
Gauging patching effectiveness
A second question that PEDIG addressed in ATS 5 is whether patching works.
The question was asked, Dr. Wallace said, because "some people question whether there is really any benefit to patching. Because few studies have included an untreated control group, it's difficult to tease out how much of the improvement was from patching and how much may have been from other factors such as glasses-wearing or a learning effect."
The ATS 5 study consisted of the control group of children with spectacle correction only if needed. The active treatment group consisted of children assigned to spectacle correction if needed, plus 2 hours of daily patching with at least 1 hour of near visual activities.