A Vision For Bionic Retinas

Few treatments exist for retina-damaging diseases such as macular degeneration and retinitis pigmentosa. And the treatments that are available simply slow progression of these diseases rather than restore lost vision.

A new polymeric device restores light sensitivity to degenerated retinas taken from blind rats, a first step toward stopping and reversing blindness caused by retinal damage. The device, developed by neuroscientist Fabio Benfenati and materials scientist Guglielmo Lanzani of the Italian Institute of Technology and coworkers, consists of layers of poly(3-hexylthiophene), indium tin oxide, and glass (Nat. Photonics, DOI: 10.1038/nphoton.2013.34).

On top of the polymer layer, the researchers placed retinas removed from the rats. When exposed to light, the polymer restored light sensitivity to the damaged retinas as measured by firing of retinal neurons. The device continued to work for more than a month. The team hopes to use the polymer for retinal implants, Benfenati says.

The work is “an exciting contribution to the field of organic bionics,” says Gordon G. Wallace of Australia’s University of Wollongong, an expert in the integration of polymers with living systems. He is particularly enthused about the prospect of being able to tune the polymer’s spectral and photoelectric properties.

The current version of the device is aimed at restoring black-and-white vision, but the team hopes to extend it to colors. Lanzani’s group has developed polymers that can discriminate among colors. But he and Benfenati still need to demonstrate that such color-sensitive polymers could restore color vision. Doing so in living animals would also require them to make sure the brain interprets signals from the device as colors.

Plus, their current device has yet to be used in live animals. “We are testing different substrates for the polymeric layer to make it suitable for surgical implant into the eye,” Benfenati says. “We hope that in four to five years, provided all in vivo tests turn out positive, we could start human testing.”