News Releases

Feb. 10, 2005

Emory Eye Center implants its first retinal chips in patients with Retinitis Pigmentosa in expanded U.S. clinical trial

( ATLANTA) An expanded clinical trial conducted by Optobionics Corporation involving the implantation of a retina mircrochip has allowed Emory Eye Center and the Atlanta Veterans Affairs

Rehabilitation Research & Development Center to implant the device in several patients. The patients all have retinitis pigmentosa with moderate-to-severe vision loss. Three centers in the United States have been chosen to conduct the expanded trial. Other than Emory and the VA Rehabilitation R&D Center they include Rush University Medical Center’s Department of Ophthalmology and the Wilmer Eye Institute at Johns Hopkins Medical Center.

Retinitis pigmentosa is a pathologic condition that is hereditary and causes progressive retinal degeneration in both eyes. It is a general term for a number of diseases that predominantly affect the photoreceptor layer or “light sensing” cells of the retina. Night blindness develops, usually in childhood, followed by loss of peripheral visual field, progressing over many years to tunnel vision and finally blindness.

At Emory Eye Center retina specialists Thomas M. Aaberg, Sr. and Jiong Yan performed the surgery recently on five patients. Another two patients are planned for mid-February.

“This experimental device may make it possible for those with retinitis pigmentosa to have a much better quality of life,” says Dr. Aaberg. “We are excited to be able to participate in this clinical trial as part of Emory Eye Center’s ongoing research and surgical procedures to fight blinding eye disease. Because Emory and the Atlanta VA Rehabilitation R&D Center met the FDA and Optobionics criteria that included surgical expertise, a strong research component and an established patient base of degenerative retinal diseases, we were able to be a part of this important study.”

Pre- and post-surgery patients are evaluated by a team of researchers working at the Eye Center and the VA Rehabilitation R&D Center including Ronald A. Schuchard, PhD and Claire Barnes, PhD.

“This clinical trial will help evaluate the potential of Optobionics’ ASR ® device to provide improved functional vision or to at least slow down the progressive vision loss” says Dr. Schuchard, principal investigator for the project. “There are very few vision rehabilitative options for patients with retinal degenerative diseases, so the opportunity to be part of evaluating a potential new rehabilitative intervention for these patients is very exciting.”

Background

In January 2000, the U.S. government’s Food and Drug Administration (FDA) authorized Optobionics to implant its Artificial Silicon Retina device in up to 10 retinitis pigmentosa patients in a two-year safety and feasibility study. The results of the study were published in the April 2004 Archives of Ophthalmology (“The Artificial Silicon Retina Microchip for the Treatment of Vision Loss from Retinitis Pigmentosa”). Among its authors is Ron Schuchard, PhD, of Emory Eye Center and the Veterans Administration Rehabilitation R&D Center.

In that two-year clinical trial, Optobionics implanted its ASR microchip into the subretinal space of ten patients with RP, to study its safety and feasibility in treating retinal vision loss.

At this time Optobionics is continuing to collect and assess clinical data from all these patients:

• No patient has shown signs of implant rejection, infection, inflammation, erosion or retinal detachment related to the implanted microchip.

• The durability of the ASR chip in this location and the long-term safety, feasibility, and suitability of this procedure, however, are yet to be determined.

ASR Device

Optobionics’ ASR microchip is designed to stimulate damaged retinal cells, allowing them to send visual signals again to the brain. This may be possible in patients with retinitis pigmentosa (RP), age-related macular degeneration (AMD) and possibly other retinal conditions. At present, the trial concentrates solely on RP patients.

The ASR microchip is a silicon chip 2mm in diameter and 25 microns thick, less than the thickness of a human hair. It contains approximately 5,000 microscopic solar cells called “microphotodiodes,” each with its own stimulating electrode. These microphotodiodes are designed to convert the light energy from images into electrochemical impulses that stimulate the remaining functional cells of the retina in patients with AMD and RP types of conditions.

The ASR microchip is powered solely by incidental light and does not require the use of external wires or batteries. When surgically implanted under the retina—in a location known as the “subretinal space”—the ASR chip is designed to produce visual signals similar to those produced by the photoreceptor layer. From their subretinal location, these artificial “photoelectric” signals from the ASR microchip are in a position to induce biological visual signals in the remaining functional retinal cells (collateral stimulation) which may be processed and sent via the optic nerve to the brain.

In pre-clinical laboratory testing done by an Emory Eye Center and Atlanta VA Rehabilitation R&D Center researcher, Machelle Pardue, PhD, animal models with retinal degeneration implanted with the ASR devices demonstrated a limited preservation of retinal function. Other tests in implanted animals have also shown that the implant is capable of actively stimulating the retina.

The Surgery

The microsurgical procedure consists of a standard ophthalmic operation called a vitrectomy and a retinotomy, plus the implantation of the chip itself.

The surgeon starts by making three tiny incisions in the white part of the subject’s eye, through which instruments are inserted. Through these incisions, the surgeon replaces the vitreous gel in the middle of the eye with a balanced salt solution, developed by Emory Eye Center’s Director of Research, Henry F. Edelhauser, PhD.

The surgeon then makes an opening in the retina through which fluid is injected: the fluid lifts up a portion of the retina from the back of the eye and creates a small pocket in the “subretinal space” just wide enough to accommodate the ASR® microchip. The surgeon then slides the implant into the subretinal space, much as one might slip a tiny coin into a pocket. Finally, the surgeon introduces air into the middle of the eye to gently push the retina back down over the implant. Over a period of one or two weeks, the air bubble is reabsorbed and replaced by fluids created within the eye. The operation typically takes about 2 hours.

Media contacts:
Joy H. Bell, 404-778-3711, jbell@emory.edu
Kathi O. Baker, 404-727-9371, kobaker@emory.edu
Janet Christenbury, 404-727-8599, jmchris@emory.edu

Media Contact: Joy H. Bell
jbell@emory.edu
404-778-3711

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