Continual progress is being made in the area of amblyopia therapy, and patients of all ages are seeing benefits. Shortened patching times, computer-based vision training, video game therapy, electronic eyeglasses and spectacle lenses that correct for predicted aniseikonia are all emerging as effective treatments.
“There’s been more movement in terms of research in amblyopia over the last 10 to 12 years than in any other area of binocular vision and childhood eye disease,” Susan Cotter, OD, MS, vice chair of the Pediatric Eye Disease Investigator Group (PEDIG), said in an interview with Primary Care Optometry News. “Many people used to think that amblyopia treatment required patching for all waking hours. However, based on the results from PEDIG’s randomized clinical trials, we found less treatment to be just as effective as more treatment. For instance, 2 hours of prescribed patching is just as effective as 6 hours for children with moderate amblyopia, and 6 hours of prescribed patching is just as effective as patching all waking hours for children with severe amblyopia.
“This means that the child wears a patch fewer hours per day, and that the parent has to supervise the child fewer hours per day, which is less of a burden for all those involved,” she said.
Another boon to compliance, according to Cotter, lies in the correction of the refractive error. “Recent PEDIG studies have shown that optical correction of refractive error alone has a true treatment effect on amblyopia beyond the immediate visual acuity gains from simply eliminating optical blur,” she said.
“We put the kids in glasses, have them come back in a month, and if acuity is improved we have them come back every 4 to 6 weeks until it stops improving,” Cotter said. “We found that about one-third of the children won’t require patching at all because they actually get better on glasses alone.”
Once visual acuity has improved, those who still require patching will have a much easier time walking around being patched because their visual acuity will be better, which often translates into better compliance with the treatment, she said.
Susan Cotter, OD, MS, pictured here with a patient, said less patching time has been found to be as effective as more.
Image: Cotter S
Another factor that could improve compliance is the finding that there is no significant clinical difference between the treatment effects of patching vs. those of using atropine drops, Cotter said.
“Before, if there were compliance problems with patching, there was nothing you could do. Now I can give the parents a choice up front: patching or atropine drops. If one doesn’t work, we can always switch to the other,” she said.
Amblyopia in adults
New evidence suggests that cortical plasticity can be recovered in adults with amblyopia, and that treatment options can actually be effective after an amblyope reaches age 8 or 9, according to Dennis Levi, OD, PhD, FAAO, dean of the School of Optometry at the University of California, Berkeley.
“Brain plasticity is more restricted in adulthood than during development. Some of these ‘brakes’ on plasticity are structural, such as perineural nets or myelin, which inhibit neurite outgrowth; others are functional, acting directly on the balance of excitation and inhibition within local neural circuits,” Levi wrote in a recently published article.
One way in which those brakes can be lifted is through perceptual learning, which is a therapy where a patient repetitively practices a difficult visual task, one that is close to the patient’s threshold ability to accomplish, Levi told PCON.