For centuries, doctors and scientists have been attempting to find a cure for blindness, without success, but a new study may change all that.
According to a team of University of California (UC) Berkeley scientists working in collaboration with researchers at the University of Munich and University of Washington in Seattle, they have discovered a chemical that temporarily restores some vision to blind mice.
The experts are now working on an improved compound that may someday allow people with degenerative blindness to see again, they say.
According to the researchers, the approach could eventually help those with retinitis pigmentosa, a genetic disease that is the most common inherited form of blindness, as well as age-related macular degeneration, the most common cause of acquired blindness in the developed world.
In both diseases, the light sensitive cells in the retina - the rods and cones - die, leaving the eye without functional photoreceptors.
However, the new chemical, known as AAQ, acts by making the remaining, normally "blind" cells in the retina sensitive to light.
Lead researcher Richard Kramer, UC Berkeley professor of molecular and cell biology, described AAQ as a photoswitch that binds to protein ion channels on the surface of retinal cells.
When switched on by light, AAQ alters the flow of ions through the channels and activates these neurons much the way rods and cones are activated by light.
"This is similar to the way local anesthetics work: they embed themselves in ion channels and stick around for a long time, so that you stay numb for a long time," Professor Kramer explained.
"Our molecule is different in that it's light sensitive, so you can turn it on and off and turn on or off neural activity."
Co-author Dr. Russell Van Gelder, an ophthalmologist and chair of the Department of Ophthalmology at the University of Washington, Seattle, said the photoswitch approach offers "real hope" to patients with retinal degeneration.
"We still need to show that these compounds are safe and will work in people the way they work in mice, but these results demonstrate that this class of compound restores light sensitivity to retinas blind from genetic disease," he added.