SUBRETINAL ELECTRICAL-STIMULATION OF THE RABBIT RETINA

A number of disorders results in photoreceptor degeneration, yet spare the inner retinal layers. We are investigating the possibility that r etinal function may be restored in such a situation by electric curren t applied from the subretinal space. In the present study, bipolar str ip electrodes receiving electric current from external photodiodes wer e implanted into the subretinal space of adult rabbits. Recordings wer e made from the scalp overlying the Visual cortex in response to photi c flash stimulation of one eye before surgery. This was compared to th e visual cortex response caused by subretinal electrical stimulation o f the same eye from an implanted strip electrode. Electric current to the strip electrode-was provided by an externally connected photodiode that was stimulated at a remote location with a photoflash. The elect rical stimulus was recordable as a brief electrical implant spike duri ng stimulation. In addition, after the implant spike, cortical respons es were obtained in response to subretinal electrical stimulation that resembled closely the normal light induced visual evoked potential pr oduced by the pre-implanted eye. These results indicate that the visua l system can be activated by electrical stimulation from the subretina l space and indicate that this approach may provide a means to restore vision to eyes blinded by outer retinal disease. (C) 1997 Elsevier Sc ience Ireland Ltd.