Photovoltaic Substitute for Lost Photoreceptors in Retinal Injury or Degeneration
Abstract
Ocular trauma or laser injury, as well as retinal degeneration, can lead to the loss of photoreceptors, resulting in permanent visual impairment. Sight can be restored to some extent by patterned electrical stimulation of the remaining inner retinal neurons. Our photovoltaic substitute of the photoreceptors directly converts light into pulsed electric current in each pixel, stimulating the second-order retinal neurons. Recent clinical tests in patients blinded by retinal degeneration demonstrated the safety of this approach and prosthetic visual acuity closely matching the 100-micrometer (um) pixel pitch of the implant (20/420). For wide acceptance of this technology, however, visual acuity should significantly exceed the level of legal blindness (20/200), and to enable visual acuity better than 20/100, pixels should be smaller than 25um. With the current flat pixel design, stimulation threshold rapidly increases with the decreasing pixel size, and it exceeds the safety limit with pixels smaller than 40um. Three-dimensional (3D) electrodes may help overcome this limitation. Building on the success of the initial testing of the 3D honeycomb-shaped approach under grant VR180018, we will study the efficacy and safety of this configuration with pixel sizes down to 20um in animal models of retinal degeneration. In particular, the studies under grant VR210011 will include optimization of the biocompatible coatings for the best integration with the retina, the optimal geometry of the honeycomb electrodes for the highest spatial resolution and selectivity of the retinal activation, as well as long-term follow-up of the retinal excitability with such implants. Upon successful completion of the proposed preclinical testing, this implant will be transferred to our industrial partner for clinical studies. This technology will benefit patients with traumatic retinopathy, laser injury, and degenerative retinal diseases. Implants with adequately small pixels should support visual acuity sufficient for reading and face recognition, thereby enabling independent and productive lifestyle to Service Members, Veterans, and their family members.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 28, 2022
- Source ID
- W81XWH2210933
Entities
People
- Daniel Palanker
Organizations
- Stanford University
- United States Army