Video Game Helps Retrain the Brain in Amblyopia

Linda Roach

May 03, 2013

Adults with amblyopia who played a video game binocularly and under conditions that reduced the visual stimulus to their better-seeing eye showed gains in stereopsis and in visual acuity (VA, logMAR units) in the amblyopic eye. The researchers saw much smaller improvements in participants who played the game monocularly.

In an article published in the April 22 issue of Current Biology, an international research group led by Jinrong Li, MD, PhD, from the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Centre, Sun Yat-sen University, Guangzhou, China, reports that after 10 hours of dichoptic training with the video game Tetris, stereopsis improved by a factor of 4 (P = .03); monocular training, in which the participants had 1 eye patched, had little effect.

After 8 weeks of training, VA in the amblyopic eyes improved from a mean of 0.51 logMAR (standard deviation [SD], ±0.09) to 0.34 logMAR (SD, ±0.09; P < .001) in the dichoptic group. Monocular play of the game resulted in minimal change in the mean VA, which went from 0.52 logMAR (SD, ±0.09) to 0.48 (SD, ±0.09; P < .05).

When the participants in the control group switched to binocular game playing for an additional 8 weeks, the investigators saw improvements similar to those initially assigned to binocular play (from a mean baseline of 0.48 logMAR [SD, ±0.09] to a postintervention mean of 0.3 [±0.11] logMAR).

These results indicate that even in adults, the brain's plasticity enables it to learn how to blend competing images from both eyes into a single view, the researchers conclude. In addition, they note, the study supports an emerging view that amblyopic eyes cannot learn to see because signals to the visual cortex are suppressed by the contralateral eye.

This explanation of amblyopia's underlying neurobiology challenges the conventional view of amblyopic eyes as "lazy" eyes that must be forced to work, study coauthor Robert F. Hess, DSc, told Medscape Medical News.

The study has caught the interest of the Pediatric Eye Disease Investigator Group, which currently is planning a multicenter clinical trial of dichoptic video game playing as a treatment for children with amblyopia. Dr. Hess is helping with the trial design.

"We've said the main problem is the 2 eyes don't work together," explained Dr. Hess, who directs the Research Department of Ophthalmology at the Research Institute of the McGill University Health Centre in Montreal, Canada. "We believe that the reason why the eye isn't working is not because it's lazy, but because it's actively inhibited by the fellow, sighted eye."

In the current study, 18 adult participants used special video-display goggles to play the video game Tetris for 10 hours, 1 hour per session, over the course of 2 weeks. The researchers rigged the goggles so that in the dichoptic group (n = 9), both eyes saw different, complementary images.

One eye saw colorful squares falling across the display, and the other eye viewed stacks of squares at the bottom. However, the image sent to the better-seeing eye was low-contrast, and the amblyopic eye's image was 100% contrast. "[The participants] can really succeed only if the information is combined between the 2 eyes," Dr. Hess said.

Other versions of the test system use a special screen filter to create the dichoptic video display on a handheld iPod Touch or an iPad, Dr. Hess said.

"This is a very promising new approach to treating amblyopia, because it doesn't involve patching the fellow eye or atropine drops to the fellow eye," Jonathan M. Holmes, MD, professor of ophthalmology at the Mayo Clinic in Rochester, Minnesota, told Medscape Medical News.

Dr. Holmes is also network chair of the Pediatric Eye Disease Investigator Group, a North American coalition of university-based and community pediatric ophthalmologists that has sponsored large interventional clinical trials of treatments for amblyopia for more than a decade.

"The Pediatric Eye Disease Investigator Group is now working with Dr. Hess to design a large multicenter randomized clinical trial to further evaluate the effectiveness of this new binocular treatment for decreased visual acuity caused by amblyopia," Dr. Holmes added.

The study was funded by national research grants in Canada, China, and New Zealand and by a Thrasher Research grant to Dr. Li. Dr. Hess and a coauthor are listed as inventors on a patent owned by McGill University, and they might receive financial compensation if commercialization occurs. Dr. Holmes has received unrestricted grants from Research to Prevent Blindness; his work with the Pediatric Eye Disease Investigator Group is funded by the National Eye Institute.

Curr Biol. 2013;23:R308-R309. Abstract