Reseachers Temporarily Restore Sight to Blind Mice With a Single Chemical Injection

[Credit: Wikimedia Commons]
A team of UC Berkeley scientists may be well on their way to finding a cure for blindness. The scientists discovered that an injection of a specific chemical directly into the eyes of blind mice temporarily restored their sight.

The two main causes of blindness are macular degeneration (which occurs naturally over time as you age) or a genetic disease called retinitis pigmentosa. Both conditions affect the light sensitive cone and rod cells in your retinas, robbing your eyes of their functional photoreceptors.

The researchers utilized a chemical called AAQ (acrylamide-azobenzene-quaternary ammonium), which acts as a photoswitch that binds to the protein ion channels on the surface of retinal cells. When the chemical is exposed to light, it changes the flow of ions in the eye to activate neurons that allow the subject to see again.

The eye of the untreated mouse on the left shows no response to light, while the pupil of the mouse on the right, which was injected with the chemical, contracts in light. [Credit: UC Berkeley]
The scientists experimented with AAQ by injecting a very small amount of the chemical directly into the eyes of genetically blind mice. The research team discovered that the method was effective after the mice shied away from a light. The procedure was further confirmed by the fact that the mice’s pupils contracted under a bright light, which meant that the mice’s brains were receiving the light signals.

So far, the photoswitch method only provides temporarily restored sight that goes away after a few hours. While this might not seem ideal, the therapy could actually benefit from being temporary.

Because the chemical eventually wears off, the patient could chose to change the dosage or discontinue the treatment in place of a new chemical therapy. Other treatments involving gene or stem cell therapies actually permanently change the retina.

The scientists are already testing newer and better versions of AAQ that could activate vision neurons for days rather than hours. There is no word on how soon or when human testing will begin, but hopefully it will be soon.

[UC Berkeley via Science Daily and Popular Science]

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