Blindness can be treated by simple ocular injection, say the scientists from the University of California at Berkeley who together with their colleagues from University of Munich and University of Washington are working on a new molecule called AAQ.
During the experiments, the researchers were able to restore the vision to a certain level in mice, blind since birth. For this purpose, a substance called AAQ was injected in the eyes, which works by transforming “blind” cells in the retina into light-sensitive ones.
Theoretically AAQ molecule can be used for the treatment of blindness in people that lose their eye sight due to AMD (age-related macular degeneration) or patients with genetic disease retinitis pigmentosa.
To begin with, scientists deduced the strain of mice genetically programmed to blindness. Vision of rodents completely disappeared few months after birth. Jabs of AAQ, injected in the eyes of these mice, temporarily restored the sensitivity to light. Pupils of the mice contracted when exposed to bright light, and they tried to avoid the bright light which they could not observe before injection.
For a normal mouse, light sensitivity is common, but the blind do not react to light, as they do not see it. Return of sensitivity in blind mice has proved that AAQ can be used to treat blindness.
AAQ (acrylamide-azobenzene-quaternary ammonium) molecule works like a photoswitch which when injected sticks to proteins on the surface of retinal cells. AAQ or photocells get switched-on by the falling light altering the flow of ions through channels which in turn activate the brain cells.
Lead author of study Richard Kramer, professor of molecular and cell biology at UC Berkeley, says that the advantage of this method is that the AAQ is a very common substance, its dosage can be changed, combined with other treatments or therapy can be discontinued if the results are unsatisfactory. New variants of AAQ with time will also improve its effectiveness.
He added that if you implant chips in patient’s eye by surgery or do some genetic modification, you don’t have any flexibility.
The study was published in the latest issue of journal Neuron. Now scientists are testing a new and improved version of AAQ, which can activate neurons for days, not hours.
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