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

Abstract

Purpose:: We have developed an artificial vision by direct optic nerve electrode (AV-DONE) and showed the efficacy and safety with animal study. The purpose of this study is to examine if this system is useful and safe in a preliminary clinical trial of the AV-DONE system to patients with retinitis pigmentosa (RP).

Methods:: Two RP patients with a visual acuity of light perception were enrolled in this trial at APEC in mexico city. Parylene coated platinum wire electrodes (0.05mm in diameter) were inserted into optic nerve disc after 3-port vitrectomy under general anesthesia.Biphasic pulses (duration: 0.25 ms/phase, frequency: 40 Hz) were applied through selected electrode the next day after implantation of electrodes. The size, shape and location of phosphene described by the patients were recorded. All stimulation sessions were performed under topical anesthesia the next day and 6 months postoperatively for patient 1 and the next day for patient 2. The wires were placed under conjunctiva. Approval from the institutional review board committee and informed consent were obtained for these cases in APEC.

Results:: Each patient could perceive phosphenes with electrical stimulation thorough each electrode. The threshold of perception for phosphenes was 0.05 mA in patient 1 and 0.07 mA in patient 2 the next day and 0.03 mA 6 months postoperatively in patient 1. The size was between those of match head and football. The shape was round or oval. The location of the phosphene was reproducible the next day in patient 1. However, those 6 months postoperatively in patient 1 and the next day in patient 2 were not reproducible. During follow-up period, visual acuity of operated eye and fellow eye of patient 1 became better than that before stimulation and no complications were found in 2 eyes.

Conclusions:: Localized phosphenes could be elicited by AV-DONE system in patients with advanced RP. These results suggest that AV-DONE has a possibility of useful artificial vision system.

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