In the search to find more effective treatments for amblyopia, most ophthalmologists agree that patching works. Where they disagree is on the number of hours needed to treat the problem.
A series of recent studies has sparked plenty of discussion on the issue. In a study published last fall, the Pediatric Eye Disease Investigator Group (PEDIG) found that prescribing six hours of daily patching for the unaffected eye of children with severe amblyopia works as well as prescribing full-time patching.1 This came on the heels of an earlier PEDIG study stating that two hours of daily patching is as effective as six hours for moderate amblyopia.2
Nonetheless, many ophthalmologists continue to argue strongly in favor of full-time occlusion therapy. It’s enough to make your head spin—especially if you throw in the PEDIG findings demonstrating that atropine eye drops given once a day to treat amblyopia work as well as the standard treatment of patching one eye.3
The PEDIG “is challenging our perception of what is effective in treating children with amblyopia,” said Sherwin J. Isenberg, MD, professor of pediatric ophthalmology at the University of California, Los Angeles. “If patching is really better, which it probably is most of the time, can we get away with fewer hours? It is important to address our conventional assumptions and see what is really true.”
A Different World
Interestingly, noted Michael X. Repka, MD, the expert clinical wisdom of 70 years ago that has served as the foundation for patching has not changed in all these years. What has changed is the American lifestyle, and perhaps to an equal extent, the way medicine is practiced in the 21st century.
“Without a doubt, life for children was simpler 40 years ago,” said Dr. Repka, professor of ophthalmology and pediatrics at Johns Hopkins University. “Today, the lives of children revolve around several daily structured activities—allowing a reduced opportunity for full-time patching. In fact, the volume of these extra activities is so pervasive that treatment is being impacted, especially in terms of compliance.”
Another 21st-century issue that must be factored into the patching equation is the physician’s time. Full-time patching, noted William E. Scott, MD, professor emeritus of ophthalmology at the University of Iowa, requires a more intense time commitment on the physician’s part because these children must be followed closely to ensure that occlusion amblyopia does not occur.
Two Hours: Less Is More
The PEDIG’s study on two-hour patching created quite a buzz in the pediatric ophthalmic community when it was published in May 2003. Dr. Repka noted that the PEDIG embarked on the study to determine whether there was a viable alternative to patching for extended periods of time, hypothesizing that two hours would be a “reasonable” period to enhance compliance from a traditionally stubborn patient population.
In the four-month randomized multicenter clinical trial, 189 children younger than 7 years with amblyopia of 20/40 to 20/80 received either two or six hours of daily patching combined with at least one hour per day of near-visual activities during patching.
Caption: Two hours, six hours or all day:
Conventional wisdom is under assault.
The investigators found similar visual acuity improvement in the amblyopic eye during both time frames, with an average of 2.4 lines of improvement in each group. The four-month visual acuity was at least 20/32 and/or improved from baseline by 3 or more lines in 62 percent of patients in each group. As Dr. Repka put it, “Anything that can make it easier for the patient and parent is an important finding.”
However, the results must be viewed with compliance in mind. Dr. Repka noted that the findings were based on the prescribed patching dosage, not the actual dosage. And since compliance was self-reported, the actual patching hours may be completely different. Moreover, the study ran only four months—a concern for those who want to see long-term follow-up data.
Six for Severe?
Another criticism leveled at the two-hour study was that the trial only included children with moderate amblyopia. However, the PEDIG trial that looked at children with severe amblyopia may help counter that concern.
The study compared full-time patching (defined as all hours or all but one hour per day) to six hours of patching per day in 175 children younger than 7 with amblyopia ranging from 20/100 to 20/400. This was combined with at least one hour during patching of near-visual activities such as coloring, tracing, reading and crafts.
After four months, the visual acuity in the amblyopic eye improved a similar amount in both groups—averaging 4.8 lines in the six-hour group and 4.7 lines in the full-time group. Most children achieved an outcome in the 20/32 to 20/63 range. Again, patching for fewer hours can ease implementation and compliance, the argument holds. And if a child doesn’t respond to six hours per day, full-time therapy may be considered. Once again, however, the study ran for four months.
Full-Time: More Is Better
Do parents want to choose the easier path? Or are they more interested in a better outcome? That is the argument Dr. Scott makes. In citing the two-hour study, he said, “The PEDIG data are quite good and scientifically sound. However, I have found in my practice over the last 30 years, with long-term follow-up data from 600 patients [who underwent full-time patching], that 96 percent of the patients achieved 20/30 vision and 60 percent achieved equal vision (20/20).
“So I ask parents, do you want a 62 percent chance of improving vision to 20/30 with part-time patching, or do you want a 96 percent chance of improving vision by choosing full-time patching? Is it worth the time and effort to you? And they almost always answer ‘Yes, we want to give our children the best possible chance of recovering vision, and we will make the effort.’ That’s what I like about full-time patching. These children have a better chance of achieving 20/20 vision or better. The other approaches work, but do they work as well?”
The debate about patching involves not only how long one should patch, but also the role of atropine eye drops. According to the 2002 PEDIG study, atropine eye drops given once a day to treat amblyopia are as effective as the standard treatment of patching one eye for moderate amblyopia.
In this trial, 419 children younger than 7 years with amblyopia and visual acuity in the range of 20/40 to 20/100 were assigned to receive either patching (ranging from six hours to all waking hours) or atropine at 47 clinical sites. The patching time was reduced or increased depending on the success of the treatment at 16 weeks.
Visual acuity in the amblyopic eye improved in both groups (improvement from baseline to six months was 3.16 lines in the patching group and 2.84 lines in the atropine group). The six-month acuity was 20/30 or better in the amblyopic eye and/or improved from baseline by 3 or more lines in 79 percent of the patching group and 74 percent of the atropine group. However, the patching group achieved 20/30 vision sooner, on average, than did the atropine group, Dr. Isenberg noted.
1 Holmes, J. M. et al. Ophthalmology 2003; 110(11):2075–2087.
2 Repka, M. X. et al. Arch Ophthalmol 2003; 121(5):603–611. See also the Editor’s Choices supplement at www.EyeNetMagazine.org, in the January 2004 issue.
3 PEDIG. Arch Ophthalmol 2002;120(3): 268–278.