Fig. 1.
Comparison of the light sensitivities of natural and artificial photoreceptor systems. Rod and cone photoreceptor sensitivities and melanopsin-expressing retinal ganglion cell sensitivity are compared with those of halorhodopsin (NpHR), wild-type channelrhodopsin 2 (ChR2), and vertebrate rhodopsin installed in various cell types. Light sensitivities are given in photons/cm2 s The wavelengths for the respective therapeutic approaches are color-coded and indicated as numbers in white. All optogenetic channel light sensitivities are based on in vitro retinal whole-mount recordings from retinal ganglion cells (Figure modified from [27])