The compounds, called prosthe6, restored visual responses in zebrafish and mouse models of retinal degeneration under ordinary ambient light. In mouse models of retinal degeneration, intraocular or topical administration restored optokinetic responses and innate light-avoidance behavior under ambient white light. Whether a drop formulation would deliver adequate concentrations to the human retina is a separate question. Light-switchable small molecules designed to substitute for lost photoreceptors by acting on the mGlu6 receptor on ON bipolar cells, the retinal cells that normally receive photoreceptor signals. Why does it matter that the compounds work in ordinary light?