Roger HighfieldBlind patients are given silicon-chip retinas
Tuesday 4 July 2000
Artificial retinas made from silicon chips have been implanted in the eyes of three patients who have lost almost all their vision, marking the first time the operation has been attempted.
All three were released from hospital the day after surgery, but it will be two and a half weeks before surgeons know if the two men and one woman, two of whom use guide dogs, can see. Prof Jose Pulido, a member of the surgical team at the University of Illinois at Chicago, said: "We've completed the first part of our journey to the Holy Grail of restoring eyesight to the blind. As far as true retinal implants are concerned, these are the first of their kind."
Preliminary tests have determined that no complications have occurred after the operations. Prof Pulido said: "There is a little bit of inflammation but surprisingly little." Surgery was carried out at the end of last week at the Chicago Medical Centre and at Central DuPage Hospital, Winfield, Illinois. The three patients, aged between 45 and 75, were all made blind by the eye disease retinitis pigmentosa.
Another of the surgeons was Dr Alan Chow, president of the Optobionics Corporation of Illinois and the inventor of the Artificial Silicon Retina with his brother, Vincent Chow. The artificial retina is a silicon microchip 2mm across and one-thousandth of an inch thick - less than the thickness of human hair - which contains approximately 3,500 microscopic cells that convert light into electrical impulses.
The purpose of the chip is to replace damaged photoreceptors, the light sensing cells of the eye, which normally convert light into electrical signals within the retina. The device is powered solely by incident light and does not require the use of external wires or batteries. While retinitis pigmentosa and other retinal diseases destroy photoreceptor cells, sufferers still have the nerve wiring to convey information to the brain.
The surgery is part of a feasibility and safety study approved by the US Food and Drug Administration to determine whether the retina could be safely implanted in the human eye. The team placed a small version of the implant in a side portion of the retina. Dr Chow said: "We hope that if the implants are able to stimulate the retina, patients may develop some degree of vision over the location of the implant within the next month."
The operation starts with three tiny incisions in the white part of the eye. Through these the surgeons introduce a miniature cutting and vacuuming device that removes the gel in the middle of the eye and replaces it with saline. They then make a pinpoint opening in the retina through which they inject fluid to lift up a portion of the retina, creating a small pocket just wide enough to accommodate the artificial retina.
Once it is inserted, they reseal the retina, introduce air into the middle of the eye to push the retina back down over the device, and close the incisions. Over one or two days, the air bubble is absorbed and replaced by fluids created in the eye.