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Six-hour patching may improve amblyopic eyes after 2-hour patching plateaus
Persistent therapy may also achieve unexpected improvement.
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When the visual acuity of a child with amblyopia appears to plateau with spectacles and patching therapy prescribed at 2 hours per day, increasing the prescribed patching to 6 hours per day may resume improvement, according to recently released study results from the Pediatric Eye Disease Investigator Group.
Susan A. Cotter, OD, MS, FAAO, vice chair of the Pediatric Eye Disease Investigator Group (PEDIG), told Primary Care Optometry News that the young children in the study showed improvement after 10 weeks when the prescribed dosage was increased from 2 to 6 hours.
“Therefore, eye care practitioners should consider an increase in the patching dosage when visual acuity stops improving with low-dose patching and residual amblyopia is still present,” she said.
Study design
At the study onset, 169 children (a mean age of 5.9 years) were randomized to either continue on with 2 hours of daily patching or to increase to 6 hours of daily patching. All but four subjects completed the 10-week primary outcome visit, lead author David K. Wallace, MD, MPH, said during a webinar discussing the results.
Patients were eligible for inclusion if they had been treated with 2 hours of daily patching for at least 12 weeks with no improvement in amblyopia acuity in two visits at least 6 weeks apart, Wallace said. If stable at this point, they were then randomized to the 2-hour group or the 6-hour group and followed for 10 weeks before the primary outcome visit.
Susan A. Cotter
Additionally, extending treatment without increasing patching dosage may also be effective in expanding improvement, Cotter said.
“Children continuing on 2 hours of daily patching also showed improvement, which I didn’t expect,” she said. “Even with a strict requirement of at least 12 weeks of 2 hours of daily patching with no measured improvement at 2 visits 6 weeks apart prior to randomization, some children continued to improve as the treatment continued.”
Evidence-based strategy developed
Based on these results, as well as results of prior PEDIG studies, the pediatric faculty at the Southern California College of Optometry (SCCO), Marshall B. Ketchum University, follow an evidence-based management strategy for young children presenting with amblyopia, according to Angela Chen, OD, MS, a faculty member at SCCO and a top subject recruiter for this study.
“First, we prescribe the optimal refractive correction and follow the child every 4 to 8 weeks until there is no further improvement in visual acuity,” Chen said.
With no prior treatment, she added, there is an average of three lines of improvement for these children.
“In cases where amblyopia persists, we prescribe either 2 hours of daily patching or 2 days per week of 1% atropine drops, with follow-up every 4 to 8 weeks until no further improvement is found,” Chen said. “Sometimes, though, we will persist for more than two consecutive visits where no improvement is observed.”
Angela Chen
“If parents are not willing to increase the patching dosage,” Cotter said, “other alternatives are to switch treatments, such as from patching to atropine, or to incorporate anti-suppression therapy. Of course, the effectiveness of anti-suppression therapies for residual amblyopia has not yet been systematically studied in a controlled fashion.”
According to Cotter, until recently, it was common practice among eye care practitioners to treat children with 6 to 12 hours of patching, even for those with moderate amblyopia (defined as 20/40 to 20/80). However, many eye care providers changed their practice patterns once PEDIG published findings demonstrating that moderate amblyopia improved similarly with both 2 and 6 hours of prescribed patching and there was no advantage in rapidity or magnitude of improvement in the 6-hour group.
“Because of this, many eye care providers decreased their initial patching dosage for moderate amblyopia to 2 hours,” Cotter said, “which is effective because prescribing fewer hours of patching reduces the treatment burden. I suspect that this leads to better overall compliance.”
However, according to the new results, prescribing 6 hours still has its uses, particularly when improvement from the 2-hour dosage tapers off, she said.
“If spectacles alone don’t work, try 2 hours of daily patching,” Wallace said during the webinar. “If that doesn’t work, or improvement stops and amblyopia is still present, then increase to 6 hours.”
This study did not look at alternate approaches, such as atropine, he said. It showed that increased patching is an effective approach, not that it is the only approach that can be effective in getting additional improvement.
Take-home message
“Basically, the take-home message of these results is ‘don’t throw in the towel too soon,’” Primary Care Optometry News Editorial Board member Joseph P. Shovlin, OD, FAAO, said in an interview. “Give the patient more time, in general, because just when you think improvement from the 2-hour patching has leveled off, a greater amount of patching time may turn out to be additionally productive.
Joseph P. Shovlin
“Also, according to the results, in the 2-hour extended group — although it did not exhibit the same benefit that the 6-hour group did — some kids continued to improve when given extended patching time,” Shovlin added. “So it really does seem reasonable to increase the dose of patching therapy time when stable amblyopia persists after 10 to 12 weeks of therapy.” – by Daniel R. Morgan