Subretinal implantation of Okayama University-type retinal prosthesis (OUReP^TM) in canine eyes by vitrectomy

Abstract

Okayama University-type retinal prosthesis (OURePTM) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. This study aims to test surgical feasibility of subretinal implantation and functional durability of dye-coupled films in the subretinal space. The dye-coupled films were implanted subretinally by 25-gauge vitrectomy in the right eye of 11 normal beagle dogs: 2 dogs served for film removal after 5-month film implantation, 3 dogs for film removal after 3-month film implantation, 3 dogs for 3-month film implantation and pathological examination, and 3 dogs for sham surgery. The surface electric potential of the removed dye-coupled films in response to light was measured by the Kelvin Probe system. At surgery, rolled-up dye-coupled films in 5 × 5 mm square size could be inserted into subretinal space of retinal detachment induced by fluid injection with a 38-gauge polyimide tip. Retinal attachment was maintained by silicone oil injection in vitreous cavity. At autopsy, the retina in all dogs maintained the ganglion cell layer, inner and outer nuclear layers while it lost the outer segments in some part. All 5 sheets of removed dye-coupled films maintained the dye color. One sheet of the 5-month implanted film showed proportional increase of surface potential in response to increasing light intensity. Subretinal implantation of OURePTM by vitrectomy was technically feasible in canine eyes, and OURePTM maintained the function of generating light-evoked surface potential after 5 months in subretinal implantation.

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 the present study, electric potential changes generated in response to light on the dye-coupled lm surface were successfully measured by the Kelvin probe. The Kelvin probe system has been renovated with humidity control of the atmosphere to measure surface electric potential of dye-coupled lms reproducibly at a steady level [17,18]. The slope-like trivial drift of baseline of electric potential in repeat episodes of lighton-and-off would be attributed to the accumulation of static electricity on the dye-coupled lm surface.…”

“…2.2 Light-evoked surface electric potential measurement Light-evoked electric potential of the lm surface was measured using a scanning Kelvin probe system (SKP5050 with a light source, Surface Photovoltage Spectroscopy SPS040, KP Technology, Highlands and Islands, UK, Fig. 2) in the surface photovoltage mode [17,18]. The dye-coupled lm was xed on a sample device under dry condition in a humidity controlled box with nitrogen gas ow (Fig.…”

Visual evoked potential in rabbits’ eyes with subretinal implantation by vitrectomy of Okayama University-type retinal prosthesis (OUReP^TM)

“…The goals of this study are two folds: the first to test surgical feasibility of subretinal film implantation by vitrectomy in rabbits, and the second to test functional durability of the implanted films. In the previous study [ 17 ], beagle dogs were used for dye-coupled film implantation. The canine study demonstrated technical feasibility of film implantation and 5-month functional durability of the implanted films.…”

“…Sophisticated techniques are required to implant surgically the multielectrode arrays. In contrast, the dye-coupled film is a soft and thin sheet which would be rolled up and inserted in subretinal space by routine vitrectomy [ 16 , 17 ].…”

“…In our previous study, the dye-coupled films were implanted subretinally in canine eyes and were also removed by vitrectomy in order to examine the feasibility of surgical techniques [ 17 ]. In this study, the dye-coupled films were implanted in normal rabbits’ eyes to be monitored with visual evoked potential.…”