Bionic eyes for blind patients
The implant, a tiny chip containing 3,500 photovoltaic cells, converts light into an electrical signal perceptible by the brain's optic nerves.
Six people who received the implant in clinical trials in 2000 reported significant improvements in their vision.
The firm which made the chip, Optobionics of Wheaton, Illinois, makes this claim on its website. Some of the patients were able to distinguish forms, the firm said.
The technique is a ray of hope for people affected by retinitis pigmentosa, a chronic, progressive disease marked by degeneration of the retina and other vision problems.
The procedure, developed by Doctor Alan Chow, takes about two hours and can be performed on a hospital outpatient basis.
First, a surgeon makes three tiny incisions, each no larger than the diameter of a needle, in the white part of the patient's eye.
The surgeon removes gel from the eye and replaces it with saline solution to maintain internal pressure in the eye.
The surgeon then makes an opening in the retina and injects fluid to create a small pocket below the retina large enough to accommodate the microchip.
After the chip is inserted, the surgeon introduces air in the middle part of the eye to push the retina back down over the implant.
No patient has shown signs of rejecting the implant or infection in the two years since the clinical trials, Chow said, presenting his research to a conference organised by the Association for Vision Research and Ophthalmology in Fort Lauderdale, Florida.
The long-term safety and durability of the Artificial Silicon Retina chip have yet to be determined, cautioned Chow.-AFP