Let There Be Light—From Artificial Retinas
 

Julia Haller sees a promising trend in retinitis pigmentosa patients implanted with tiny computer chips.

Ophthalmologists fighting the ravages of retinitis pigmentosa may have finally found some daylight. While participating in a three-way trial initiated by a Chicago group, Wilmer ophthalmologist Julia Haller in December began implanting “artificial retinas” into eight patients ranging in age from their 20s to 50s who were in advanced stages of the blinding disease. “And they’ve all done beautifully with it,” Haller reports. “People are already getting larger visual fields” from the earlier Chicago study, she says, and the first signs from the Baltimore patients look promising.

The technology—which relies on a 2-millimeter-diameter silicon computer chip that is surgically implanted in the eye—appears to benefit from electrical microcurrents within the tiny chip itself, which is 25 microns thick. The chip contains 5,000 microscopic solar cells that convert light energy from images into electrochemical impulses that stimulate the remaining functional retinal cells of RP patients.

One of Haller’s research associates,

Gislin Dagnelie, says many vision experts initially doubted the technology’s viability because the rods and cones within the eye do more than simply gather light; they also amplify it more than 1,000 times. How could microscopic solar cells possibly be up to such a task, especially since they’d be attempting to stimulate a compromised secondary layer of cells below where the healthy cells once lay?

“The chip itself doesn’t give vision,” Dagnelie explains, “but we think the microcurrents released by the chip may be causing neighboring cells to release chemical messengers that improve the health of the remaining rods and cones in the center of the retina, one quarter of an inch away from the chip itself.”

Haller also speculates that when the foreign body is implanted in the eye, a healing response ensues that rejuvenates tissue quality.

In any case, Haller is encouraged by this stage of the clinical trial. “Is this technology feasible? Yes. Is it an acceptably low risk? Up to this point, yes. Does it help? There are encouraging signs. What’s still unknown is how much it helps and how long it will last.”