AAO: Camera Chip Provides Sight in Retinitis Pigmentosa

Oct. 18, 2010— -- CHICAGO -- A tiny array of light-sensing diodes restored a measure of sight to a small number of patients with retinitis pigmentosa, a researcher said here.

Eleven patients with the condition, who had been blind for 13 to more than 40 years, had the chip implanted in their retinas with no major ill effects, said Walter G. Wrobel of Retinal Implant AG of Tubingen, Germany, manufacturer of the device.

In a late-breaking oral presentation at the American Academy of Ophthalmology's annual meeting here, Wrobel also showed videos portraying a participant in the pilot study who was able to recognize letters and words and identify fruits by their shapes.

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Other participants had similar results, Wrobel said.

Retinitis pigmentosa is a condition in which photoreceptors progressively die off, starting at the retinal periphery, and eventually wipe out the ability to see at all. There is currently no effective treatment to halt the process, although various therapies can help patients make the most of their remaining sight.

The Retinal Implant chip comprises 1,500 light-sensing diodes, each 50 microns across, capable of generating seven images per second that flash for approximately 2 microseconds. It is surgically inserted just behind the retina -- normally just under the fovea, Wrobel said -- delivering electrical pulses to the retinal cells that otherwise are unable to respond to light.

Wrobel said the chips used in the trial required connection to an external power supply, with a wire passing through the skull and out behind the patient's left ear. But the company has now developed a wireless power supply, he said.

He described five sets of tests of visual ability in the study. Patients were asked to describe what they could make of so-called Landolt rings -- shapes like a thick letter C, projected in various orientations on a screen -- and of fruits laid on a table in front of them.

They were also shown block letters two to three inches high, white on a black background at waist height.