High-Resolution Retinal Prosthesis for Restoring Sight to Patients Blinded by Retinal Injury or Degeneration
Abstract:
Ocular trauma or laser injury can result in loss of sight due to damage of photoreceptors. Similarly, retinal degeneration leads to a gradual loss of photoreceptors and associated visual impairment. In these conditions, the inner retinal neurons are preserved to a large extent, and visual perception can be restored by electrical stimulation of the remaining retinal network. We developed photovoltaic replacement of photoreceptors, which directly converts light into pulsed electric current in each pixel, stimulating the nearby inner retinal neurons. Clinical trial with such implants having 100 micrometer pixels confirmed feasibility of such approach and demonstrated that spatial resolution closely matches the pixel pitch (20/420). For a wide-spread acceptance of this technology, prosthetic visual acuity should exceed 20/100, which requires pixels smaller than 25 micrometers. We are developing and testing a novel 3-dimensional electro-neural interface to significantly decrease the stimulation threshold and reduce the pixel size down to 10-20 micrometers. During the current reporting period, we demonstrated that the inner retinal cells migrating into the 3-D implants retain healthy appearance, and that tertiary neurons remain outside the wells. We also show that retinal migration does not negatively affect its electrical excitability, proving feasibility of the 3-D implants for high resolution retinal prosthetics.