The animal was deeply anesthetized with isoflurane and the first eye was enucleated. After the enucleation of the second eye, the animal was euthanized by CO2 inhalation. The retinal flatmounts were prepared as previously described (10 (link)). Briefly, an incision was made along the corneal limbus, the lens and sclera were removed, and radial cuts were made to relieve the curvature. The flat-mounted retina was transferred to a glass bottom dish (MatTek Corp.) and incubated at room temperature in the Ames’ medium (A1420, Sigma-Aldrich) oxygenated with 95%O2/5%CO2.