Visual Restoration - Retinal Prosthesis, Stem Cells and In Between
In outer retinal degeneration, such as Retinitis Pigmentosa or Age related Macular Degeneration, the retinal photoreceptors degenerate while the inner retinal neurons are relatively preserved. Stimulation of these neurons by various technologies was shown to elicit visual percepts. Nevertheless, the visual acuity obtained by current retinal prosthesis is still very poor, probably due to a combination of technical and neural effects. An alternative emerging technology is the transplantation of photoreceptors differentiated from stem cells. Although this is a promising approach, the complexity of the photoreceptor differentiation process, pathology of the host retinal pigment epithelium and inadequate integration of the photoreceptors into the host retina, make this approach very challenging. In this lecture I will present our experience with both photovoltaic retinal prosthesis and with generation of photoreceptors from human embryonic stem cells, as potential technologies for restoration of sight. I will also introduce our novel head mounted DMD based projection system for natural and prosthetic visual stimulation in behaving animals.