Thiran Jayasundera and David N Zacks, from the University of Michigan Kellogg Eye Center performed the surgeries for patients with end-stage retinitis pigmentosa (RP), a degenerative and blinding eye disease. (Agencies)
"We are pleased with both patients' progress at this point, and we are hopeful and optimistic that the artificial retina will enable them to see objects, light and people standing before them," Jayasundera said.
"We believe the device will help them navigate a little better at home, be more independent, and have the pleasure of seeing things that the rest of us take for granted," said Jayasundera.
The device Argus II Retinal Prosthesis System, developed by Second Sight Medical Products Inc of Sylmar, California, was approved by the US Food and Drug Administration last year. The retinal prosthesis is not activated until the patient has sufficiently recovered from surgery.
The patient then undergoes training to adapt to the new vision, a process that can take from one to three months.
The surgeons performed the first Argus II implant on January 16 and a second implant on January 22.
Retinitis pigmentosa is an inherited retinal degenerative disease that causes slow but progressive vision loss due to a gradual loss of the light-sensitive retinal cells called rods and cones, researchers said.
Patients with RP experience gradual loss of side vision and night vision, and later of central vision, which can result in near blindness.
The Argus II Retinal Prosthesis System is surgically implanted in one eye. The individual wears glasses equipped with a camera that captures images and converts them into a series of small electrical pulses.
The pulses are transmitted wirelessly to the prosthesis and its array of electrodes on the surface of the retina. These pulses are intended to stimulate the retina's remaining cells, resulting in the corresponding perception of patterns of light in the brain.
The patient then learns to interpret these visual patterns, thereby regaining some visual function.
To be eligible to receive the retinal prosthesis, individuals must be 25 or older with end-stage retinitis pigmentosa that has progressed to the point of having "bare light" or no light perception in both eyes.
Thiran Jayasundera and David N Zacks, from the University of Michigan Kellogg Eye Center performed the surgeries for patients with end-stage retinitis pigmentosa (RP), a degenerative and blinding eye disease.