Chemical Restores Vision in Lab Study

July 26, 2012
An international team of researchers was able to temporarily restore some vision in blind mice by treating their retinas with a chemical called acrylamide-azobenzene-quaternary ammonium (AAQ). While the research is still at an early stage, AAQ, or a derivative, might be used someday to restore vision in people who are blind from advanced retinal degenerations, such as retinitis pigmentosa (RP) or age-related macular degeneration.

In their experiments, the scientists injected small amounts of AAQ into the eyes of mice, which had lost all of their rods or cones, the cells that normally provide vision, to degenerative disease.

AAQ enabled the mice to respond to light, as simple tests demonstrated. The pupils of the treated mice contracted when exposed to light, and the animals exhibited natural light-avoidance behaviors. The scientists acknowledge that they can’t tell what exactly the mice are seeing.

AAQ enabled bipolar, amacrine and ganglion cells in the retina to respond to light. These cells are normally not light-sensitive, but often survive after rods and cones are lost to RP and other retinal degenerations.

AAQ is a potential alternative to emerging optogenetic treatments, in which gene therapy is used to enable ganglion cells, and potentially other surviving cells in a degenerating retina, to respond to light. Researchers believe a single administration of gene therapy will last several years, whereas the effects of a single injection of AAQ are temporary, lasting only a few days. However, a potential advantage of an AAQ-based treatment is that it can be immediately stopped, or the dosage can be changed, if there are undesirable effects.

The researchers are now working to identify ways to provide sustained delivery of AAQ to the retina. They also need to conduct more tests to evaluate AAQ’s safety, toxicity and effectiveness.

The international team is headed by Dr. Richard Kramer from the University of California, Berkley, and includes Dr. Russell Van Gelder, from the University of Washington, Seattle, who presented preliminary results of the AAQ research at the recent Optogenetics Therapies for Vision workshop co-hosted by the Foundation Fighting Blindness. The most recent results of the AAQ research were published online on July 26, 2012, in the journal Neuron.