Cortical responses elicited by photovoltaic subretinal prostheses exhibit similarities to visually evoked potentials

Abstract

We have previously developed a wireless photovoltaic retinal prosthesis, in which camera-captured images are projected onto the retina using pulsed near-IR light. Each pixel in the subretinal implant directly converts pulsed light into local electric current to stimulate the nearby inner retinal neurons. Here we report that implants having pixel sizes of 280, 140 and 70μm implanted in the subretinal space in rats with normal and degenerate retina elicit robust cortical responses upon stimulation with pulsed near-IR light. Implant-induced eVEP has shorter latency than visible light-induced VEP, its amplitude increases with peak irradiance and pulse duration, and decreases with frequency in the range of 2-20Hz, similar to the visible light response. Modular design of the arrays allows scalability to a large number of pixels, and combined with the ease of implantation, offers a promising approach to restoration of sight in patients blinded by retinal degenerative diseases.

Differential Loss of Prolyl Isomerase or Chaperone Activity of Ran-binding Protein 2 (Ranbp2) Unveils Distinct Physiological Roles of Its Cyclophilin Domain in Proteostasis

“…Disturbances in transmission through this pathway are manifested in neurodegenerative diseases, such as ALS, multiple sclerosis, optic atrophies, and several retinopathies (107)(108)(109)(110). We examined cone and rod photoreceptor functions by light-and dark-adapted ERGs and transmission through the visual pathway, including retinal ganglion cells, in VEPs.…”

Interactions of Prosthetic and Natural Vision in Animals With Local Retinal Degeneration

“…The subretinal implantation technique was similar to the one previously reported by our group. 10,15 Animals were anesthetized with a mixture of ketamine (75 mg/kg) and xylazine (5 mg/kg) injected intramuscularly. A 1.5-mm incision was made through the sclera and choroid 1.5 mm posterior to the limbus; the retina was lifted with an injection of saline solution, and the implant was inserted into the subretinal space.…”

Restoration of visual function by expression of a light-gated mammalian ion channel in retinal ganglion cells or ON-bipolar cells

“…Direct electrical stimulation of the surviving inner retina has proven to be successful in restoring useful vision (6)(7)(8). One approach employs surgically implanted photovoltaic or electrode arrays to stimulate retinal ganglion cells (RGCs) (8) or bipolar cells (BCs) (6,7) directly in the inner nuclear layer (INL) of the degenerated retina, and promising results in clinical trials have led to US Food and Drug Administration approval for the Argus II device (Second Sight Medical Products, Inc.) (8).…”

“…One approach employs surgically implanted photovoltaic or electrode arrays to stimulate retinal ganglion cells (RGCs) (8) or bipolar cells (BCs) (6,7) directly in the inner nuclear layer (INL) of the degenerated retina, and promising results in clinical trials have led to US Food and Drug Administration approval for the Argus II device (Second Sight Medical Products, Inc.) (8). The electrical implants demonstrate that inner retinal neurons in blind patients can respond to appropriate stimulation and lead to a useful visual percept allowing simple navigation and object recognition.…”