“…The remaining neural portion of the retina (bipolar and ganglion cells), however, remains anatomically and functionally intact beyond the death of PRs (Strettoi and Pignatelli, 2000;Chang et al, 2002). This has led to the development of various therapeutic strategies, such as implanting stem cells to replace lost PRs (Bellapianta et al, 2022;Li et al, 2013), retinal prostheses electrically activating the remaining neural retina (Weiland and Humayun, 2014), or the use of synthetic photoswitchable ligands (Polosukhina et al, 2012) or optogenetic proteins that turn bipolar or ganglion cells into light-sensitive "replacement photoreceptors" (Bi et al, 2006;Lagali et al, 2008;Cehajic-Kapetanovic et al, 2015;van Wyk et al, 2015;Sengupta et al, 2016;Berry et al, 2019). Two optogenetic gene therapies aiming to express channelrhodopsin-2 (ChR2) in retinal ganglion cells-the output neurons of the retina-have recently entered clinical trial to restore vision in patients suffering from advanced RP (NCT02556736 and NCT03326336).…”