抄録
Retinal prosthesis has been investigated as an innovative treatment to outer retinal degeneration such as retinitis pigmentosa. Epiretinal stimulation and subretinal stimulation were developed as the methods to stimulate the residual retinal neurons. Both systems, however, have some difficulties in safety of electrode implantation because of direct attachment of the implanted electrodes to the retina. We proposed the novel retinal prosthesis method, suprachoroidal transretinal stimulation (STS), the electrodes of which are implanted in the sclera and the vitreous body. This approach of retinal stimulation can reduce surgical insult on the implantation. Electrophysiological studies with normal and RCS rats revealed that STS was able to evoke focal excitation on superior colliculus and that its threshold was comparably low to epiretinal or subretinal stimulation (Kanda et al., 2004). To evaluate the area activated by STS quantitatively, the response probability elicited by STS and the distance from the scleral electrode to the receptive field of LGN relay cells of cats were measured for each unit and each stimulus intensity. The units with high response probability were limited near the scleral electrode, and the radius of the activated area at half maximum response was 1.8 degrees on 100 and 150 uA of STS. These physiological evaluations indicated that STS is a good candidate as well as other retinal prosthesis. The integrated efforts of neuroscientists, ophthalmologists and engineers should be required to realize the retinal prosthesis. [J Physiol Sci. 2007;57 Suppl:S30]
