Retinal pigment epithelium (RPE) cells form unique patterns that can be used to track changes in this important layer of tissue at the back of the eye, researchers from the National Eye Institute (NEI) have found. Using a combination of adaptive optical imaging and a fluorescent dye, the researchers used the RPE patterns to track individual cells in healthy volunteers and people with retinal disease. The new finding could provide a way to study the progression and treatment of blinding diseases that cause RPE.