People who have become blind might be able to train their brains to see again. It takes some time, however — a study published in PLOS Biology reports that over the long term, patients with total blindness from a condition called retinitis pigmentosa were able to teach themselves to see again with the help of a light-sensitive electrode implanted on their retina, and lots of practice.
The implant, called the Argus II retinal prosthesis, transmits visual signals to the brain by stimulating cells in the retina, a tissue layer in the eye that is sensitive to light, the nonprofit open-source publisher PLOS explained in a statement. After their surgery, the study in PLOS Biology notes, six out of seven blind people with the condition could “detect high-contrast stimuli,” and over time responded more to visual cues. The patients’ advancements included things that could affect quality of life for the blind: After a period of time, the subjects were able “to perform a few easy behavioral tasks, such as moving independently in space, locating a large bright square on a screen and reading large, 100-percent contrast characters.”
The National Eye Institute notes that retinitis pigmentosa, which is genetic, causes cells in the retina to break down, at first causing difficulty with peripheral vision and seeing in the dark and potentially leading to total blindness. It estimates that about 1 in 4,000 people have the disorder, which can appear as early as childhood. The institute explains that the Argus II implant on the retina, which “has not proven effective” but is approved by the federal Food and Drug Administration for use in some retinitis pigmentosa patients, wirelessly transmits information from a camera to the electrode on the retina, which then sends the information to the brain.
The new study findings are perhaps most important for cases in which blind people receive a retinal implant but do not experience immediately restored visual function, such as those who have been without vision for long periods of time. The resilience of an adult brain’s primary visual cortex, the image processing center, “is limited, especially after many years of blindness.” But the patients in this specific study show it is possible to regain visual function through an implant: “The recovery of vision depended on the amount of time and practice the subject experienced with the implant, implying that the reorganization process takes time to develop.”
According to PLOS, the researchers from the University of Pisa, Italy, who were funded by the European Research Council, studied the subjects both before and after receiving the implant. Post-implant and with the help of an MRI, they detected increased brain activity associated with the patients’ recognizing visual stimuli such as flashing lights. This new information “can be exploited in the development of new prosthetic implants,” the PLOS statement said.
Source: Castaldi E, Cicchini GM, Cinelli L, Biagi L, Rizzo S and Morrone MC. Visual BOLD Response in Late Blind Subjects with Argus II Retinal Prosthesis. PLOS Biology. 2016.