Second Sight Developing Vision-Restoring Device Connected to the Brain
When it comes to restoring vision to the blind, researchers may soon bypass the eye entirely and go straight to the brain.
Second Sight Medical Products, developer of the Argus II, the first “bionic retina” to receive regulatory approval in the United States and Europe, is adapting its technology to connect to the visual cortex, a region in the brain responsible for processing visual information. The company successfully implanted a model of its cortical prosthesis, known as the Orion I, in an animal study, and is planning to launch a human trial in early 2017.
“Because we’re bypassing the front of the eye, the retina and the optic nerve, we may be able to treat nearly all forms of blindness, including glaucoma, diabetic retinopathy and vision loss from infections and trauma,” says Robert Greenberg, M.D., Ph.D., chief executive officer at Second Sight. “The Orion I may even restore vision in people who have had their eyes removed due to disease or injury.”
The Orion I is similar in design to the Argus II. Both systems use a video camera mounted on a pair of glasses to capture images and send them to a video processing unit (VPU). After processing, the images are transmitted wirelessly to a 60-electrode array. With the Argus II, the array is attached to the retina. It sends visual information via the optic nerve to the brain. The Orion I’s newly developed array, however, sits on the surface of the visual cortex.
A new VPU, 25 times faster than the current one, is being tested for both the Orion I and Argus II. “The faster VPU will support newer software to enhance the resolution and visual experience for users of both devices,” says Dr. Greenberg. “Using a new image-processing algorithm called Acuboost, we were able to get one [Argus] patient’s vision to 20/200.”
Users of the Argus II perceive patterns of light, which the brain learns to interpret as vision. The device has enabled people profoundly blind from retinal degeneration to see shapes, recognize large letters and significantly improve mobility. Second Sight developers believe users of the Argus II and Orion I will have similar vision restoration.
The Argus II was initially implanted in people with retinitis pigmentosa and related conditions. Second Sight is now testing the device in people with age-related macular degeneration at the University of Manchester in the United Kingdom.
Unlike the Argus II, which is implanted by a retinal surgeon, the Orion I will be installed by a neurosurgeon. While placing a device on the surface of the brain is more invasive, and inherently more risky, the procedure may actually be simpler.
“The surgery for the Argus II is more delicate, because the retina is like wet, one-ply tissue paper,” explains Dr. Greenberg. “Interfacing something to the retina was very challenging, much more so than brain tissue, which is pretty tough. It’s a lot more robust than the retina.”
Though developing the surgery for the Argus II was more difficult, Second Sight decided to develop a retinal device first, because of the reduced risk for the patients. “With the retinal implant, we’re putting something in a blind eye, so if something went wrong, the patient wasn’t losing vision,” says Dr. Greenberg. “With the Orion I, we’re putting something in a normal brain, so there is no room for error. So, we wanted to make sure we had mature technology before tackling the brain implant.”
More than 100 people are using the Argus II, which is available at 20 centers of excellence in the U.S. and Europe. Second Sight expects to have nearly 40 centers up and running at the end of the year. The centers will likely also implant patients with the Orion I, when it becomes available.