Dye-Coated Retinal Prosthesis Shows Promise for Restoring Vision

March 17, 2015

Researchers at Okayama University in Japan are planning to launch a clinical trial later this year for an innovatively simple retinal prosthesis they’ve developed to restore vision in people blind from retinitis pigmentosa (RP) and related conditions. Known as the Okayama University-type retinal prosthesis, or OUReP™, it’s a plastic film coated with a light-sensitive dye that is implanted beneath the retina. In a lab study, the device preserved vision in rodents with advanced RP. The investigators published the study’s results in the Journal of Artificial Organs.

Often referred to as artificial or bionic retinas, prostheses are designed to replace photoreceptors, the cells in the retina that process light and make vision possible. People blind from advanced retinal diseases have lost most or all of their photoreceptors. 

Most retinal prosthetic technologies, including the Argus II and the Alpha IMS, use video cameras to capture images. An array of electrodes, implanted adjacent to the retina, then convert the images into electrical signals, which are sent to the brain, where they’re interpreted as vision.

The OUReP is much simpler. There is no camera or electrodes, and it does not need an electrical current, which usually requires an external power source. Instead, the dye on the film captures light coming into the eye and stimulates surviving retinal neurons, including ganglion and bipolar cells, to send visual information back to the brain.

Toshihiko Matsuo, M.D., Ph.D., the lead investigator on the project, says implanting the OUReP beneath the retina should be relatively straightforward in humans. “The sheet can be implanted in the subretinal space, using surgical methods established more than 20 years ago,” he explains. “Therefore, the implantation procedure should be technically feasible for vitreoretinal surgeons.”

He adds that the prosthesis’ polyethylene film has been used safely in other medical implants for humans, and the dye has not shown any toxicity in testing thus far.

In addition to preserving vision, the OUReP appears to reduce the loss of retinal cells in the rodents, suggesting that the dye may be protective. However, the investigators caution that more research is needed to better understand the effect.

“The simplicity of this approach is very attractive. Fewer components mean reduced risk for failures and complications,” says Stephen Rose, Ph.D., chief research officer, Foundation Fighting Blindness. “With that said, we need to see if the Okayama prosthesis can restore meaningful vision in humans. That’s the bottom line.”