Chemical restores vision in blind mice

A team at the University of Munich and U.S. scientists say they discovered a chemical that temporarily restores some vision to blind mice. Lead researcher Richard Kramer of the University of California at Berkeley said the chemical AAQ acts by making the remaining, normally "blind" cells in the retina sensitive to light. AAQ is a photoswitch -- a kind of sensor that detects the presence of light -- 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, Kramer said. "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," Kramer said in a statement. "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." However, because the chemical eventually wears off, it might offer a safer alternative to other experimental approaches for restoring sight, such as gene or stem cell therapies, which permanently change the retina, Kramer said. "The advantage of this approach is that it is a simple chemical, which means that you can change the dosage, you can use it in combination with other therapies, or you can discontinue the therapy if you don't like the results," Kramer said. The findings were published in the journal Neuron.