Speaker: Daniel Palanker, Ph.D.
Director of the Hansen Experimental Physics Laboratory and Professor of Ophthalmology
Date: Wednesday, November 18, 2020
Time: 1:00-2:00 PM EST
Zoom – check email for link or contact email@example.com
Title: “Photovoltaic Restoration of Sight in Age-related Macular Degeneration”
Retinal degenerative diseases lead to blindness due to loss of the “image capturing” photoreceptors, while neurons in the “image-processing” inner retinal layers are relatively well preserved. Information can be reintroduced into the visual system using electrical stimulation of the surviving inner retinal neurons. We developed a photovoltaic substitute of photoreceptors which convert light into pulsed electric current, stimulating the secondary retinal neurons. Visual information captured by a camera is projected onto the retina from augmented-reality glasses using pulsed near-infrared (~880nm) light. This design avoids the use of bulky electronics and wiring, thereby greatly reducing the surgical complexity. Optical activation of the photovoltaic pixels allows scaling the number of electrodes to thousands. In preclinical studies, we found that prosthetic vision with subretinal implants preserves many features of natural vision, including flicker fusion at high frequencies (>30 Hz), adaptation to static images, antagonistic center-surround organization and non-linear summation of subunits in receptive fields, providing high spatial resolution. Results of the clinical trial with our implants (PRIMA, Pixium Vision) having 100μm pixels, as well as preclinical measurements with 75 and 55μm pixels, confirm that spatial resolution of prosthetic vision can reach the pixel pitch. Remarkably, central prosthetic vision in AMD patients can be perceived simultaneously with peripheral natural vision. For broader acceptance of this technology by patients who lost central vision due to agerelated macular degeneration, visual acuity should exceed 20/100, which requires pixels smaller than 25μm. I will describe the fundamental limitations in electro-neural interfaces and 3-dimensional configurations which should enable such a high spatial resolution. Ease of implantation of these wireless arrays, combined with high resolution opens the door to highly functional restoration of sight.
Daniel Palanker is a Professor of Ophthalmology and Director of the Hansen Experimental Physics Laboratory at Stanford University. He received MSc in Physics in 1984 from the State University of Armenia in Yerevan, and PhD in Applied Physics in 1994 from the Hebrew University of Jerusalem, Israel. Dr. Palanker studies interactions of electrical field with biological cells and tissues, and develops optical and electronic technologies for diagnostic, therapeutic, surgical and prosthetic applications, primarily in ophthalmology. In the range of optical frequencies, his studies include laser-tissue interactions with applications to ocular therapy and surgery, and interferometric imaging of neural signals. In the field of electro-neural interfaces, he is developing highresolution photovoltaic retinal prosthesis for restoration of sight and implants for electronic control of organs. Several of his developments are in clinical practice world-wide: Pulsed Electron Avalanche Knife (PEAK PlasmaBlade, Medtronic), Patterened Scanning Laser Photocoagulator (PASCAL, Topcon), Femtosecond Laser-assisted Cataract Surgery (Catalys, J&J), and Neural Stimulator for enhancement of tear secretion (TrueTear, Allergan). Photovoltaic retinal prosthesis for restoration of sight (PRIMA, Pixium Vision) is in clinical trials.
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