Researchers look for clues to improve artificial vision for patients with retinitis pigmentosa

Researchers look for clues to improve artificial vision for patients with retinitis pigmentosa

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SEOUL: Important findings that may improve the performance of retinal prostheses that make up artificial vision for visually impaired individuals have been reported by a team of Korean researchers.
The Korea Institute of Science and Technology (KIST) announced that Dr. of the Center for Bioimorosystems. The Brain Science Institute, a research team led by Mesun Im, had found that retinal nerve signals arising from electrical stimulation change depending on the disease in mice affected by the external retina. Degeneration. The research was done in collaboration with Professor Shelley Fried’s laboratory at Harvard Medical School, Massachusetts General Hospital.
The research was published in the journal IEEE Transactions on Neural Systems and Rehabilitation Engineering.
Degenerative diseases of the retina, such as retinitis pigmentosa and age-related macular degeneration, mainly destroy photoreceptor cells, which convert light into electrochemical signals, leading to profound vision loss. Currently, there is no available cure for these diseases.
Fortunately, retinal ganglion cells are known to avoid the conditions by which “artificial vision” is available. An array of microelectrodes can be implanted behind the eyeball to stimulate ganglion cells to transmit visible neural signals in the brain again by the electric rash imposed by those microelectrodes. This is the basic working principle of retinal prosthetic devices. Although many retinal prosthesis have been commercialized, one of the problems preventing widespread application is enormous performance variation in patients with an unknown cause.
The KIST research team had delayed a potential source of performance variation and found that the level of disease progression could be significant. He designed a longitudinal study and conducted experiments using mice at different stages of retinal degeneration. Those mice gradually lost their vision due to a genetic mutation, similar to those with retinitis pigmentosa.
Researchers recorded electrically evoked neural activities of retinal ganglion cells from animals at different ages and tried to correlate those artificial vision signals to disease progression. They reported that the magnitude and stability of electrically evoked responses decreased as retinal degeneration advanced.
Response stability is particularly important for retinal prostheses because they periodically replicate the artificial scene using repetitive electrical stimuli. For example, when a retinal prosthesis user stares at the letter “K”, a neural signal representing a “K” is required to repeat the electrical stimuli.
Otherwise, that is, if the stability of the response is too low, electrical stimuli can transmit neural signals, meaning different letters such as “L,” “R,” or “S”, thus explaining the artificial user correctly. It becomes difficult to do what it is or not. Is watching The Kist study suggests that it is likely to occur in the severely thin retina.
During a series of experiments to assess the degree of similarity in different neural signals arising from repeated electrical stimuli of the same condition, they found that the stability of the response declined with a steadily increasing rate while the normal retina. Showed high continuity in.
The study’s lead authors, Drs. Young-Joon Yoon and Drs. Jae-Ik Lee stated, “Even though a user fixes their gaze, they are likely to transmit different neural signals to the brain when their retrograde retina is repeated. Electrical stimulation. Perhaps, it is electrically- Could be the reason for the poor perception of artificial vision developed. ”
“Retinas exhibit different patterns of progression in degenerative disease patients. Our results suggest that carefully selecting retinal transplant candidate patients is important by assessing the level of progression of retinal degeneration of each patient,” Dr. Vesoon Im said. “We are studying hardware and software approaches for improved quality of artificial vision for patients with late stage degeneration.”


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