Visual Evoked Potential Recovery by Subretinal Implantation of Photoelectric Dye‐Coupled Thin Film Retinal Prosthesis in Monkey Eyes With Macular Degeneration

Abstract

Retinal prosthesis or artificial retina is a promising modality of treatment for outer retinal degeneration, caused by primary and secondary loss of photoreceptor cells, in hereditary retinal dystrophy and age‐related macular degeneration, respectively. Okayama University‐type retinal prosthesis (OUReP) is a photoelectric dye‐coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. The dye‐coupled films were implanted by vitreous surgery in the subretinal space of monkey eyes with macular degeneration which had been induced by cobalt chloride injection from the scleral side. A pilot 1‐month observation study involved 6 monkeys and a pivotal 6‐month observation study involved 8 monkeys. Of 8 monkeys in 6‐month group, 3 monkeys underwent dye‐coupled film removal at 5 months and were observed further for 1 month. The amplitude of visual evoked potential which had been reduced by macular degeneration did recover at 1 month after film implantation and maintained the level at 6 months. Optical coherence tomography showed no retinal detachment, and full‐field electroretinograms maintained a‐wave and b‐wave amplitudes, indicative of no retinal toxicity. Pathological examinations after 6‐month implantation showed structural integrity of the inner retinal layer in close apposition to dye‐coupled films. The implanted films which were removed by vitrectomy 5 months later showed light‐evoked surface electric potentials by scanning Kelvin probe measurement. The photoelectric dye‐coupled film (OUReP), which serves as a light‐receiver and a displacement current generator in the subretinal space of the eye, has a potential for recovering vision in diseases with photoreceptor cell loss, such as retinitis pigmentosa and age‐related macular degeneration.

Photoelectric Dye-Coupled Polyethylene Film: Photoresponsive Properties Evaluated by Kelvin Probe and <i>In Vitro</i> Biological Response Detected in Dystrophic Retinal Tissue of Rats

“…In our previous study, implantation of the photoelectric dye-coupled polyethylene lm in retinal dystrophic RCS rats led to vision recovery in the behavior test [14,29], and induced electroretinographic and visual evoked potential responses [29,30]. We also showed that the amplitude of visual evoked potential, which was reduced by macular degeneration in monkey eyes, was recovered by subretinal dye-coupled lm implantation [31]. The durability of dye-coupled lms in the subretinal space of monkey eyes was assessed for half a year [31].…”

“…We also showed that the amplitude of visual evoked potential, which was reduced by macular degeneration in monkey eyes, was recovered by subretinal dye-coupled lm implantation [31]. The durability of dye-coupled lms in the subretinal space of monkey eyes was assessed for half a year [31].…”

Vision evaluation by functional observational battery, operant behavior test, and light/dark box test in retinal dystrophic RCS rats versus normal rats

“…In our previous study, we showed the recovery of visual evoked potential amplitudes in monkey eyes with macular degeneration by subretinal dye-coupled film implantation in the period of 6 months [36]. The dye-coupled film was also implanted in eyes of dogs [37] and rabbits [38, 39] to show the safety and surgical feasibility.…”

Artificial Organs 2018: A Year in Review

“…Toshihiko Matsuo et al of the Okayama University Medical School and Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama City, Japan, reported on their retinal prosthesis (OUReP) which consists of a photoelectric dye‐coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. The dye‐coupled films were implanted by vitreous surgery in the subretinal space of monkey eyes with macular degeneration which had been induced.…”