A novel chemical temporarily restored some vision to blind mice, and this success may eventually lead to a treatment to help people with degenerative blindness see again, according to a recent study.
Those who could benefit include people with retinitis pigmentosa and age-related macular degeneration (AMD). Retinitis pigmentosa is a genetic disease that is the most common inherited form of blindness, while AMD is the most common cause of acquired blindness in the developed world.
In both diseases, light sensitive cells in the retina called rods and cones die and leave the eye without functioning photoreceptors.
The mice used in this study had genetic mutations that made their rods and cones die within months of birth. Injections of the chemical AAQ into the eyes of the blind mice temporarily restored their light sensitivity, according to the study published in the journal Neuron.
AAQ makes the remaining, normally "blind" cells in the retina sensitive to light, explained lead researcher Richard Kramer, PhD, a professor of molecular and cell biology at the University of California, Berkeley.
This approach "offers real hope to patients with retinal degeneration," study co-author Russell Van Gelder, MD, PhD, chair of the ophthalmology department at the University of Washington in Seattle, said in the news release.
"We still need to show that these compounds are safe and will work in people the way they work in mice, but these results demonstrate that this class of compound restores light sensitivity to retinas blind from genetic disease," he added.
The researchers noted that the chemical eventually wears off, which may make it a safer alternative to other experimental methods for restoring sight, such as gene or stem cell therapies, which permanently change the retina. Chemical treatment is also less invasive than implanting light-sensitive chips in the eye, the researchers 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. As improved chemicals become available, you could offer them to patients. You can't do that when you surgically implant a chip or after you genetically modify somebody," Dr. Kramer explained.
However, experts note that while studies involving animals can be useful, they frequently fail to produce similar results in humans.
The research was supported by the US National Institutes of Health's National Eye Institute and Research to Prevent Blindness.