Camera chip offers hope to people with blindness-linked condition

Tuesday, October 19, 2010

WASHINGTON - Scientists have offered new hope to patients with retinitis pigmentosa, a group of genetic eye conditions that leads to incurable blindness.

A tiny array of light-sensing diodes brought-back a measure of sight to some patients with retinitis pigmentosa, said a researcher.

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.

Wrobel said after the implant the patient was able to recognize letters and words and identify fruits by their shapes, reports ABC News.

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.

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 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.

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 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.

Finally, patients were placed in a room with people in it and were encouraged to approach and touch them.

Wrobel noted that the addition of regular eyeglasses appeared to improve the visual acuity in many patients.

Twelve patients were initially recruited into the study, but one patient died just before the chip was to be implanted, he said.

Among the 11 patients receiving the device, none suffered retinal detachment, major hemorrhages, inflammation or vitreoretinal tractions-the major safety concerns for such a procedure.

The findings were discussed at the at the American Academy of Ophthalmology’s annual meeting. (ANI)

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