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Blind for 20 Years, Implant Partially Restores Sight

New York (Jan 27, 2010)

An eye exam chart

By implanting an experimental electronic eye device, a doctor at NewYork-Presbyterian/Columbia University Medical Center has partially restored the sight of a woman previously blind from retinal disease. The woman is able to see light and make out figures for the first time in 20 years, explained lead researcher Lucian V. Del Priore, MD, PhD, an Attending Surgeon at NewYork-Presbyterian Hospital and a Professor in the Department of Ophthalmology at Columbia University College of Physicians and Surgeons.

The implant is currently being investigated for the treatment of retinitis pigmentosa, a progressive disease that causes cell death in the outer layer of the retina &ndash the area of the eye responsible for detecting light. In a healthy person, the cells in the outer layer of the retina detect light and then send a signal to the brain. In a person with retinitis pigmentosa, the outer layer of the retina does not transmit any signal to the brain. The person cannot see any light and cannot tell, for example, if his or her eyes are open or closed.

Dr. Lucian V. Del Priore
Dr. Lucian V. Del Priore

How the Device Works

In patients with retinitis pigmentosa, the cells in the inner layers of the retina still function so the electronic eye implant is used to bypass the damaged cells in the outer layer of the retina and connect with the healthy nerve cells in the inner retina. The device works as a three-part system. The first part is an external video camera that is mounted on a pair of eyeglasses worn by the patient. That image is processed and then a signal is transmitted wirelessly to the second part of the system &ndash a microprocessor (a small computer chip) implanted on the outside of the eye under the lid. This microprocessor then translates the information into a series of electrical pulses that are sent to the third part of the device: a tiny patch of 60 electrodes implanted near the deeper, healthy cells in the inner retina. From here, the electrical impulses trigger nerves in the inner retina and then send the image to the brain. The images that a patient can see are very basic. However, for a patient who has had no vision initially, the level of vision afforded by this device can represent a remarkable improvement, Dr. Del Priore said.

Illustration of the Argus II implant
Illustration of the implant
(Second Sight Medical Products Inc.)

The device works best with high contrast images, meaning a white object on a black background or vice versa. It also works best at night, when there is high contrast between lighted objects and the dark background. The patient who received the device five months ago at NewYork-Presbyterian/Columbia University Medical Center is now able to see large letters on a computer monitor, and she also describes being able to see street and traffic lights as well as light coming in through the window of her front door. Her vision continues to improve, Dr. Del Priore said.

Learning to use the implant properly requires a major commitment on the part of the patient, as it takes several years of rehabilitation to learn how to use the device and interpret the patterns that the patient sees. This part of the visual training involves using direct electrical stimulation of the retina; successful interpretation of the image by the patient requires that she participate in one day per week of visual training in a laboratory and then practice the techniques learned at home.

The surgery required to implant the device took approximately 5 to 6 hours with the patient under general anesthesia. While the patient treated by Dr. Del Priore and colleagues did not experience any serious side effects, he said that there are surgical complications that can result from surgery of that length, such as infection, low eye pressure, and movement of the device after surgery.

Currently, the device is only being investigated for use in the treatment of retinitis pigmentosa. Dr. Del Priore said that patients with conditions like macular degeneration would not benefit markedly from the current generation of the implant device, as the additional vision gained from the device is not worth the risk of surgery and length of rehabilitation the patients would have to undergo. Dr. Del Priore believes that the technology will continue to improve and offer a higher image resolution in the future. "At that point, we will have more experience and it is likely that use of multi-electrode arrays will likely expand to other eye diseases," he said.

Faculty Contributing to this Article:

Lucian V. Del Priore, MD, PhD, is an Attending Surgeon at NewYork-Presbyterian Hospital and a Professor in the Department of Ophthalmology at Columbia University College of Physicians and Surgeons.

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