The artificial vision allows the patient to see brightness and shapes, thereby providing enhanced navigation of the patient’s environment and help with day-to-day activities.
Emory Eye implanted its first patient in December 2014, the 14th such surgery in the United States. The Argus II® device was FDA approved in 2013. This post-approval trial at Emory, along with those at other locations in the country, will enable researchers and clinicians to further the development of sight restoration.
The prosthetic system is designed for those over 25 years of age with severe retinitis pigmentosa (RP) and minimal or no light perception. The device provides electrical stimulation of the retina to induce visual perception in blind patients, bypassing damaged photoreceptors. Thus far, the device is only available to viable candidates who have advanced RP.
Retinitis pigmentosa is an inherited, degenerative eye disease of the retina caused by abnormalities of the rods and cones (photoreceptors) that leads to progressive vision loss. The disease can manifest itself in light/dark adaptation issues, peripheral vision loss (tunnel vision) and, less often, central vision loss in advanced stages. There is no current cure. RP affects about 1 in 4,000 people in the United States, according to government statistics.
Retina surgeon Jiong Yan, MD, is the principal investigator of this post-approval trial at Emory. “This is the first treatment available for patients affected by retinitis pigmentosa,” says Yan. “It is groundbreaking because it is the first time we are able to restore sight, albeit artificial vision, to someone who has lost vision completely from the disease.”
“This device, Argus II, is revolutionary,” says Emory Eye Center Director Timothy W. Olsen, MD. “While this remains a somewhat primitive form of what normally sighted individuals would consider vision, I predict that this is the first of many versions of artificially generated sight. Enabling those who are blind to experience light, images and shapes is remarkable indeed. Also, watching the smile grow across the face of an individual who hasn’t seen light in over 40 years was very rewarding. Dr. Yan is a superb surgeon and leads this important program at Emory.”
How it works
A miniature video camera housed in a patient’s glasses captures a scene. The video is sent to a small patient-worn, computerized video processing unit – VPU, where it is processed and transformed into instructions that are sent back to the glasses via a cable, then transmitted wirelessly to an antenna in an implant. The signals then pass to an electrode array that emits small pulses of electricity.
These pulses bypass the damaged photoreceptors and stimulate the retina’s remaining cells, which then transmit the visual information along the optic nerve to the brain. This process is intended to create the perception of patterns of light that patients can learn to interpret as visual patterns.
The treatment following implantation is visual rehabilitation and occupational therapy for a few weeks to months enabling the patient to have maximum benefit from the prosthesis.
Patients are studied for five years to collect information about the performance and safety of the system.