In Canada, age-related macular degeneration affects more than 800,000 Canadians over the age of 40.

Researchers are working on light-sensitive switches they believe can help restore sight to patients with macular degeneration.

These optical switches can trigger a chemical reaction, spark a muscle contraction, activate a drug or stimulate a nerve cell with just a flash of light, according to a team of scientists at UC Berkeley-LBNL Nanomedicine Development Center, a research center newly created by the University of California, Berkeley, and Lawrence Berkeley National Laboratory.

The researchers want to equip cells of the retina with photoswitches, which they believe would restore light sensitivity in people with degenerative blindness such as macular degeneration.

"We're asking the question, 'Can you control biological nanomolecules — in other words, proteins — with light?,'" Ehud Y. Isacoff, the centre's director and a professor of molecular and cell biology at UC Berkeley, said in a media release.

"If we can control them by light, then we could develop treatments for eye or skin diseases, even blood diseases, that can be activated by light. This challenge lies at the frontier of nanomedicine," Isacoff said.

Light sensitivity restored

After the researchers injected photoswitches into the eyes of rats thathad macular degeneration— which destroys the rods and cones, the retina's photoreceptors —they discovered some light sensitivity had been restored to the remaining retinal cells.

They are hoping to develop the viruses that can carry the optical switches into the correct cells, so that their biological functions can be controlled effectively.

"The research will focus on one major application: restoring the response to light in the eyes of people who have lost their photoreceptor cells, in particular, the rods and cones in the most sensitive part of the retina," Isacoff said.

Loss of photoreceptors — the light detectors in the retina — is the major cause of blindness in the United States. One in four people over age 65 suffers vision loss as a result of the condition, the most common diagnosis being macular degeneration.

In Canada, age-related macular degeneration affects more than 800,000 Canadians over the age of 40. The late stage of this disease, associated with vision loss, is the most common cause of legal blindness in people over the age of 50 in the Western world.