Three blind mice may no longer need their white canes, thanks to a new chemical which may one day help people with degenerative blindness see again.
The chemical, called AAQ, could help those with retinitis pigmentosa, a genetic disease that is the most common inherited form of blindness and age-related macular degeneration, the most common causes of acquired blindness in the developed world.
In those diseases, the light sensitive cells in the retina—the rods and cones—die, leaving the eye without functional photoreceptors. The new drug acts by making the remaining, normally “blind” cells in the retina sensitive to light.
AAQ becomes the 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.
The effect 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. The molecule is different in that it’s light sensitive, so you can turn it on and off and turn on or off neural activity.
Because the chemical eventually wears off, it may offer a safer alternative to other experimental approaches for restoring sight, such as gene or stem cell therapies, which permanently change the retina. It is also less invasive than implanting light-sensitive electronic chips in the eye.
