(A) Schematic of the experimental protocol. Four- to 6-week-old male and female pigmented Abca4−/−Rdh8−/− mice or BALB/c mice were exposed to bright light at 10,000 lux for 30 min, followed by the procedures as indicated. IHC, immunohistochemistry; OCT, optical coherence tomography; SLO, scanning laser ophthalmoscopy; ERG, electroretinogram; TPM, two-photon microscopy; RNA-seq, RNA sequencing. (B) After 4′,6-diamidino-2-phenylindole (DAPI) staining, retinal cryosections from Abca4−/−Rdh8−/− mice were observed under a fluorescence microscope. Retinas were collected from Abca4−/−Rdh8−/− mice at the time points indicated including 3 hours, 1 day, and 7 days after light exposure. Red arrows mark areas showing the thinning of the OPL. (C) Toluidine blue–stained retinal sections from Abca4−/−Rdh8−/− mice unexposed to bright light or at 3 hours after light exposure. White lines outline the OPL. (D) Electron microscopy of retinal sections from Abca4−/−Rdh8−/− mice unexposed to bright light or at 3 hours after light exposure. M, mitochondrion; R, synaptic ribbon in photoreceptor synaptic terminal. Red arrows, cytoplasmic vacuolation.