Sight for the blind?

In landmark surgeries at the University of Illinois at Chicago Medical Center on June 28, and at Central DuPage Hospital, Winfield, Illinois on June 29, the first artificial retinas made from silicon chips were implanted in the eyes of three blind patients who have lost almost all their vision from retina pigmentosa.

All three patients were released from the hospital the following day. Preliminary tests have determined that no complications have occurred.

The surgical team for all three operations consisted of Drs. Alan Chow, President and CEO of Optobionics Corporation of Illinois, the company that invented and developed the artificial retina, Gholam Peyman, Professor of Ophthalmology and Co-Director of Vitreoretinal Surgery at Tulane University Medical Center, and Jose Pulido, Professor and Head of the Department of Ophthalmology and Visual Sciences at the University of Illinois at Chicago. ‘We’ve completed the first part of our journey to the Holy Grail of restoring eyesight to the blind,’ Dr. Pulido said.

The Artificial Silicon Retina (ASR) was invented by Dr. Alan Chow and his brother Vincent Chow, Optobionics’ Vice President of Engineering. It is a silicon microchip 2mm in diameter and one thousandth of an inch thick—less than the thickness of human hair. Preliminary laboratory studies were performed in conjunction with Dr. Neal Peachey and his research group at the Edward Hines, Jr. VA Hospital in Chicago.

The ASR contains approximately 3,500 microscopic solar 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. Loss of photoreceptor cells occurs in persons with retinitis pigmentosa (RP) and other retinal diseases. All three patients who received the implants have lost almost all their vision from retinitis pigmentosa. The two men and one woman, two of whom use guide dogs, are between 45 and 75 years of age.

The landmark surgeries performed in the two area hospitals were part of a feasibility and safety study approved by the Food and Drug Administration to determine whether the ASR could be safely implanted and tolerated in the human eye. ‘In this study, we are evaluating the safety and feasibility of the ASR by placing a small version of the implant in a side portion of the retina. The operations to place the implants in this location were all successfully completed. 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,’ said Dr. Chow.

The microsurgical procedure starts with three tiny incisions in the white part of the subject’s eye, each incision no larger than the diameter of a needle. Through these incisions, 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 from the back of the eye, creating a small pocket in the ‘subretinal space’ just wide enough to accommodate the ASR.

The surgeons then enlarge the pocket opening and insert the implant into the subretinal space. Finally, they reseal the retina over the ASR, introduce air into the middle of the eye to gently push the retina back down over the device, and close the incisions. Over a period of one or two days, the air bubble is reabsorbed and replaced by fluids created within the eye.

According to Dr. Peyman, ‘The use of the subretinal space to hold a device that artificially stimulates the retina seems a logical step in replacing the loss of photoreceptor cells of the retina. If the implant is tolerated well and is able to successfully stimulate the retina, it may open up new opportunities for restoring sight in patients with the end stages of retinitis pigmentosa.’