This editorial in the April issue of Ophthalmology addresses lessons learned from the amblyopia treatment studies conducted by the Pediatric Eye Disease Investigator Group (PEDIG) since its establishment in 1997. The editorial's authors, Michael X. Repka, MD, MBA, and Jonathan M. Holmes, BM, BCh, say the PEDIG clinical trials have shown that initial spectacle correction is the first step of treatment and on its own will effectively treat many cases of amblyopia. Beyond that, patching, atropine and Bangerter filters are effective treatments, even in dosages once considered ineffective.
However, they note that even when treatment is administered as part of a clinical trial, a substantial proportion of children are left with residual amblyopia. As a result of PEDIG, treatment for amblyopia caused by anisometropia, strabismus or both can now be more evidence-based than in the 1990s, but many questions remain unanswered.
PEDIG results found that the treatment burden can be dramatically reduced for most children with amblyopia by not starting occlusion or pharmacological penalization initially and waiting a few months for improvement from spectacles alone. Some children will never need additional treatment, while others will have better amblyopic eye visual acuity when additional active treatment is initiated, likely improving compliance.
PEDIG research also found that atropine is as effective as patching in the initial active treatment of amblyopia. Parental questionnaires indicated that atropine was better tolerated than patching in terms of adverse effects, social stigma and compliance.
Follow up is continuing through the age of 15 years of the cohort enrolled in PEDIG's first patching versus atropine study. Thus far, results have indicated that the amblyopia treatment benefit persisted through age 10 years without a mean visual acuity loss, but residual amblyopia remains in a large proportion of children.
While many parents and clinicians have thought of amblyopia treatment as having a reasonably short course, PEDIG investigators found that more than 85 percent of children continued to be prescribed treatment after the first six months. Drs. Repka and Holmes say discussing treatment duration with parents may improve understanding of amblyopia treatment and compliance.
PEDIG studies also found that smaller patching doses than previously used and tested were effective. They say it is reasonable to initiate therapy with a lower dose but to increase treatment intensity for children who do not completely respond.
PEDIG research similarly has found that a smaller atropine dose produced mean improvement in visual acuity comparable to that of a larger dose, allowing the recommendation of starting with the lower dose.
A PEDIG randomized clinical trial of patching two hours per day versus a blurring Bangerter filter over the sound eye found a similar mean improvement in amblyopic eye visual acuity. These results combined with superior parental acceptance suggests that the filter is an acceptable third choice for initial active treatment if improvement with spectacles alone is incomplete.