Researchers have identified distinct differences among the cells comprising a tissue in the retina that is vital to human visual perception. The scientists discovered five subpopulations of retinal pigment epithelium (RPE) — a layer of tissue that nourishes and supports the retina’s light-sensing photoreceptors. Using artificial intelligence, the researchers analyzed images of RPE at single-cell resolution to create a reference map that locates each subpopulation within the eye.