Effect of RPE65 inhibitors on mouse cone function in vivo during and after prolonged exposure to background light. Cone b-wave sensitivity was monitored during a 30-min exposure of 3-mo-old Gnat1^−/− mice to bright 300-cd/m² white background light (gray bars) and then for 35 min in darkness. (A) Compared with control DMSO treatment (n = 6), cones from mice treated with emixustat (n = 10) were equally desensitized by the background light but had largely suppressed subsequent dark adaptation. (B) In contrast, in mice treated with MB-001 (n = 8), cones gradually desensitized during background adaptation and had suppressed subsequent dark adaptation. (C) Treatment with QEA-B-001-NH₂ (n = 6) had no effect on the function of cones in background light or during the subsequent dark adaptation. Data are presented as means ± SEM.