Novel disposable injector (OUReP Injector) tested in experimental aphakic eyes of rabbits for subretinal implantation of Okayama University-type retinal prosthesis (OUReP)

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 reports a novel disposable injector to insert the dye-coupled film in subretinal space of the eye by vitreous surgery in rabbits. The injection system composed of two separate parts, injector and loader. A circular film in 5-10 mm diameter was first pulled into a transparent tube of the loader with a commercial 25-gauge forceps. The loader tube was joined with a sleeve to tube tip of the injector. The film in the loader was pushed with a plunger for the loader into the injector tube tip. The loader with the sleeve was removed from the injector tip, and the tube tip with the film was filled with solution. Bleb retinal detachment was induced in 8 experimental aphakic eyes of rabbits by infusing solution into subretinal space with a 38-gauge polyimide tip, and a retinal tear was made at the edge of retinal detachment with 25-gauge diathermy. The injector tip with the film was inserted from 3 mm-wide scleral incision into vitreous and then into subretinal space. The film was released into subretinal space by pushing the plunger with index finger while the injector body was held with thumb and other fingers. The plunger was pushed back automatically by a coil spring inside the injector. Dissection after surgeries confirmed successful implantation of 4 films in 5 mm diameter and 4 films in 7 mm diameter into subretinal space of each rabbit eye. The film insertion by the injector was technically feasible at vitreous surgery in rabbit eyes.