PEDIG making strides in amblyopia

Take-home: Studies by the Pediatric Eye Disease Investigator Group have led to evidence-based treatment of amblyopia.

Reviewed by David K. Wallace, MD, MPH

Durham, NC-In the 18 years of the organization’s existence, The Pediatric Eye Disease Investigator Group (PEDIG) has tackled a number of challenges.

Prime among them, according to PEDIG Chairman David K. Wallace, MD, MPH, are questions regarding how well glasses-alone treat amblyopia, the effectiveness of patching in older children, the effect of near activities on the results of patching, and cessation of visual acuity improvement with patching.

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The most current and 18th of the Amblyopia Treatment Studies (ATS) is a comparison of binocular treatment of amblyopia with patching in a randomized trial of children aged 5 to less than 17 years old, with the primary goal of determining if binocular treatment is noninferior to patching in younger children.

“If binocular treatment is just as good as patching, then that would be a game-changer, and we would likely want to offer this treatment option to parents,” said Dr. Wallace, professor of ophthalmology and pediatrics, Duke Eye Center, Durham, NC.

The second study goal is to determine if binocular treatment is superior to patching in older children.

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Among the inclusion criteria is an amblyopic eye visual acuity of 20/40 to 20/200 and wearing of appropriate spectacle correction for at least 16 weeks, or stable vision on two visits 4 weeks apart. Patients will be randomly assigned to play the binocular game “Hess falling blocks” (similar to Tetris) 1 hour daily or to 2 hours of daily patching.

To be eligible for the study, patients must be able to align the nonius cross in the game and to score at least one line on the game, Dr. Wallace explained.

Patients will be assessed at 4, 8, 12, and 16 weeks for monocular distance visual acuity, Randot stereoacuity, and ocular alignment, and patients and parents will complete a diplopia questionnaire.

Highlights of the ATS

Highlights of the ATS

Dr. Wallace reviewed some of the important research published by the PEDIG that laid the groundwork for the most current study.

The earliest studies investigated the effects of patching. In ATS1, investigators found that patching and atropine result in similar improvements after 4 months of treatment.

ATS2 dealt with the dosing of the initial treatment. Two or 6 hours of patching resulted in similar improvement of 2.4 lines of vision with moderate amblyopia. In patients with severe amblyopia, 6 hours of patching and full-time patching had similar results (4.8 and 4.7 lines of vision, respectively). When patching was stopped, about 25% of children lost 2 lines or more of vision.

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ATS3 evaluated 507 older children aged 7 to 18 years who were randomly assigned to optical correction alone versus optical correction and patching and, for the younger children only, atropine. Results indicated that in children aged 7 to 12 years augmented treatment was superior, with 53% of those using augmented treatment improving by 2 or more lines, compared with 25% in the optical correction group. In the older children, augmented treatment did not make a difference when including those with/without previous treatments.

“There was an age effect over time with differences in treatment,” he said. “There was no difference in the oldest patients.”

However, when investigators looked only at children who had not been treated previously, improvement occurred even among those patients who were older.

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“So, patching often does work in older children, especially for those with no previous treatment,” Dr. Wallace said.

Regarding spectacle use, ATS5 showed that spectacle use alone improved amblyopia an average of almost 2 lines of vision after 5 weeks of therapy.

“This was a robust improvement with spectacles alone,” he said.

The same study also showed that after the spectacle improvement stopped, patching for 2 hours daily resulted in more improvement than use of spectacles alone.

The next step was a look at the effect of near activities on patching in ATS6. More than 400 young children 3 to less than 7 years of age were randomly assigned to near or distance activities with 2 hours of patching daily. The primary outcome at 8 weeks showed no difference in the mean improvement between the near and distance groups (2.5 and 2.6 lines of vision, respectively).

Severe cases of amblyopia

In children with severe amblyopia, “there was a slight suggestion that near activities were a bit beneficial at 17 weeks,” Dr. Wallace said.

“Near activities do not enhance the effect of patching, although there might be a small positive effect in children with severe amblyopia,” he said.

An evaluation of bilateral refractive amblyopia in ATS7 found that spectacles improved the binocular vision by about four lines of vision after 1 year of treatment.

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ATS13 involved optical treatment of strabismic amblyopia. Participants were aged 3 to under 7 years, had not previously worn spectacles or received amblyopia treatment, and had strabismus in spectacles.  The study found that after 18 weeks of treatment in spectacles alone, amblyopic eye visual acuity had improved an average of 2.6 lines.

This raised an interesting question, according to Dr. Wallace: How can amblyopia improve with spectacles alone when the child remains strabismic in spectacles?

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“Possibly the amblyopic eye fixes during some activities and takes advantage of the newly focused image in the glasses,” Dr. Wallace speculated.

“Glasses-alone results in substantial improvement even in those patients who remained strabismic,” he said. “The advantage of a trial of glasses first is that some children will never need patching or atropine.”

ATS15 tested the result of increased patching after the positive effects of patching stopped.  These study patients were treated with 2 hours of patching daily. After the visual improvement stopped, they were randomly assigned to 2 or 6 hours of daily patching. After 10 weeks, investigators found that 6 hours was superior to 2 hours, with 40% of children in the 6-hour group achieving two or more lines of improvement compared with 18% in the 2-hour group.

David K. Wallace, MD, MPH

E: david.wallace@duke.edu

This article was adapted from Dr. Wallace’s presentation during Pediatric Subspecialty Day at the 2014 meeting of the American Academy of Ophthalmology. Dr. Wallace receives funding from the National Eye Institute.