Artificial Vision by Direct Optic Nerve Electrode (AV-DONE) for a Blind Patient With Retinitis Pigmentosa

Abstract

Purpose: : We have developed an artificial vision by direct optic nerve electrode (AV-DONE) and previously reported the results for 2 patients with retinitis pigmentosa (RP), with a visual acuity of light perception. We are now reporting the results of a totally blind patient with RP.

Methods: : An RP patient, with a visual acuity of no light perception, was enrolled in this acute clinical trial at APEC in Mexico City. Three Parylene-coated platinum wire electrodes (0.05mm in diameter) were inserted into the optic nerve disc after 3-port vitrectomy under general anesthesia. Biphasic pulses were then applied through a selected electrode under topical anesthesia the day following the implantation of the electrodes. The size, shape, color and location of phosphenes described by the patient were recorded for every stimulation. Approval from the Institutional Review Board Committee in APEC and informed consent were obtained for this case.

Results: : The patient could perceive phosphenes with electrical stimulation through each of the electrodes. The threshold of perception for phosphenes, with a duration of 0.25 ms/phase and the frequency of 40 Hz, was 0.03, 0.02 and 0.01 mA for each electrode, respectively. The sizes ranged between those of a match head and an apple. The shapes were round, oval or linear. The colors of the phosphenes were white, yellow or white-yellow. The phosphenes seemed to focally localize with the same parameter of electrical stimulation. The area of all the phosphenes was smaller than those from the former patients with a visual acuity of light perception. No complications were found during surgery and the electrical stimulation session.

Conclusions: : Phosphenes could be elicited by the AV-DONE system in a totally blind patient with advanced RP, suggesting that AV-DONE has the possibility of becoming a useful artificial vision system for blind patients.

Keywords: optic nerve • clinical (human) or epidemiologic studies: systems/equipment/techniques • retinitis