The retina — the light-sensitive tissue at the back of the inner eye that translates images to the brain — is something of a mystery.
“No one fully understands the code that the retina uses to communicate with the brain,” Van Gelder says. What is known is that the millions of cells in the retina are grouped into families that sense and encode different types of information: motion, direction, contrast and radiance, for example.
And for two of the diseases that cause retina damage and lead to blindness — age-related macular degeneration
and retinitis pigmentosa — there is no cure. At least, not yet. Enter AAQ, a compound that blocks potassium channels, the connectors between cells that, as potassium flows back and forth, allow neurons to communicate.
A few years ago, organic chemist Dirk Trauner, Ph.D., modified AAQ to become light-sensitive. He and his colleagues at UC Berkeley — Richard Kramer, Ph.D., John Flannery, Ph.D., and Ehud Isacoff, Ph.D. — then conducted an experiment. They put brain tissue in a petri dish, added AAQ and inserted an electrode. The result? They found that AAQ rendered the tissue light-sensitive. They then began experimenting with retinas from blind mice, thinking that AAQ might be able to restore vision.
In the meantime, Van Gelder and his colleagues had developed an efficient tool to study and record the activity of many photo receptors at once: multi-array electrodes. When Van Gelder saw Kramer present AAQ findings at a conference, he had a revelation.
“The little light bulb that went off in my head,” he says, “was that our technique would be a very rapid way to demonstrate if AAQ had the potential to restore vision.”