Neuroprotective Effect of the Subretinal Artificial Silicon Retina

Abstract

Abstract: : Purpose: To evaluate possible neuroprotective effects of the subretinal artificial silicon retina (ASR) by measuring retinal function and photoreceptor preservation in RCS rats implanted at an early stage of degeneration. Methods: Three week old RCS rats were implanted with an active ASR in one eye while the other eye was implanted with an inactive ASR, underwent a sham surgery, or served as an unoperated control. Retinal function was measured with ERGs before and after implantation. The number of photoreceptor nuclei were measured in plastic sections obtained from a subset of rats that were euthanized at 8 weeks post-implantation. Results: While retinal function declined in all groups, preservation of retinal function occurred in eyes implanted with the ASR. Eyes implanted with the active ASRs showed significantly larger dark-adapted b-wave amplitudes than eyes implanted with inactive ASRs, sham operated or unoperated. In comparison, the dark-adapted a-wave decreased in amplitude equally in all groups. Counts of photoreceptor nuclei revealed a significantly larger number of photoreceptors directly overlying the implant in eyes implanted with an active or inactive ASR compared to unoperated or sham controls. However, no significant differences in photoreceptor numbers were detected between the eyes implanted with the active and inactive ASR. Conclusions: These results indicate that the subretinal ASR may have a temporary protective effect on the RCS retina. While photoreceptor cell counts at 8 weeks did not reveal a significant difference between active and inactive ASR implanted retinas, the ERG data suggest that electrical stimulation provides a protective effect.

Keywords: electroretinography: non-clinical • microscopy: light/fluorescence/immunohistochem • animal model