Ph.D. Candidate: Elton Ho
Research Advisor: Daniel Palanker
Date: Tuesday, March 10, 2020
Time: 12 noon
Location: ChEM-H / Neuro E153
Title: Restoring Vision with Electronic Photoreceptors: from Petri Dish to Patients and Back
Treatments of neurological diseases using electro-neural interfaces are rapidly advancing. Inspired by the deep brain stimulators for Parkinson’s patients and by cochlear implants for the deaf, we developed a photovoltaic subretinal prosthesis for restoring vision to patients blinded by retinal degeneration.
Our “electronic photoreceptors” replace the function of the natural photoreceptors lost due to age-related macular degeneration – they convert incident light into electric current to convey the visual information to the secondary neurons in the retina by electrical stimulation. Images captured by a camera on the augmented-reality glasses are projected onto the subretinal photovoltaic implant using pulsed near-infrared light. Patients with such prosthesis can read with acuity closely matching the pixel size of the implant currently used in a clinical trial.
I will first describe how perception of the pixelated images improves with resolution and contrast. Then I will review the characteristics of the retinal response to pulsatile electrical stimulation, including multiple features of the natural retinal signal processing preserved in the network-mediated retinal stimulation. I will then present electrophysiological and behavioral studies in rodents demonstrating the visual acuity and contrast sensitivity achievable with the next generation implants. Finally, I will describe our progress in scaling pixel size down to cellular dimensions.