Second Sight’s Retinal Prosthesis System Benefits Blind Patients

It may not cure blindness, but the Argus II Retinal Prosthesis System from Second Sight Medical Products Inc. can improve the vision of blind patients, according to a clinical study.

The company recently announced positive three-year results post-implant of the Argus II from a multi-center trial in a paper titled, “Long-Term Results from an Epiretinal Prosthesis to Restore Sight to the Blind.” The clinical study involved 30 patients implanted with the Argus II at 10 centers throughout the United States and Europe. Three types of visual function tests were performed using computer-run assessments: square localization (i.e. object detection), direction of motion (i.e. motion detection) and discrimination of oriented gratings (i.e. visual acuity). Two types of real-world orientation and mobility (O&M) tests also were performed: a test where subjects were asked to locate and touch a door, as well as a test where subjects were asked to follow a white line on the floor. In the absence of existing validated quality of life tools for this population, a Functional Low-vision Observer Rated Assessment (FLORA) also was performed by independent visual rehabilitation experts at the request of the U.S. Food and Drug Administration (FDA) to assess the impact of the Argus II system on the subjects’ everyday lives, including extensive interviews and tasks performed around the home.

Of the 30 subjects tested, 29 remained implanted with functioning Argus II systems three years after the original implantation. Results showed the Argus II System helped improve visual function and O&M up to three years. In addition, up to 89 percent of subjects performed statistically better with the Argus II system implanted compared with native residual vision in visual function tasks in the third year. During the trial, up to 80 percent of the subjects reported better functional vision and overall quality of life; no patients reported any negative effects. Second Sight executives claim the trial results support the long-term safety profile and benefit of the Argus II for individuals who are blind due to retinitis pigmentosa (RP).

“The data from this study is quite remarkable for these patients who, previously, had little to no light perception, living in a world that we could consider complete darkness,” said Allen C. Ho, M.D., F.A.C.S., director of Retina Research at Wills Eye Hospital and professor of Ophthalmology at Thomas Jefferson University in Philadelphia, Pa. “The fact that these individuals have increased independence, being able to navigate through their home, walk through doorways and cross streets, is truly life changing.”

Earlier results from this trial were used to gain approval of the Argus II by the FDA and European regulators. Company executives noted the Argus II System is the first and only retinal implant to secure both approvals.

Second Sight’s Argus II System provides electrical stimulation that bypasses the defunct retinal cells and stimulates remaining viable cells inducing visual perception in individuals with severe to profound retinitis pigmentosa. The Argus II works by converting images captured by a miniature video camera mounted on the patient’s glasses into a series of small electrical pulses, which are transmitted wirelessly to an array of electrodes implanted on the surface of the retina. These pulses are intended to stimulate the retina’s remaining cells, resulting in the perception of patterns of light in the brain. The patient then learns to interpret these visual patterns, thereby regaining some visual function. The system is controlled by software and is upgradeable, which may provide improved performance as new algorithms are developed and tested.

Based in Sylmar, Calif., Second Sight develops, manufactures and markets implantable visual prosthetics to help blind people gain greater independence. Enrollment is underway in a trial to test the safety and utility of the Argus II Retinal Prosthesis in individuals with Dry Age-related Macular Degeneration. Second Sight also is developing the Orion I Visual Cortical Prosthesis to restore some vision to individuals who are blind due to causes other than preventable or treatable conditions. The company’s European Headquarters is located in Lausanne, Switzerland.