Pyridinium bisretinoid A2E (A2E) is a fluorophore that can be isolated from lipofuscin in the retinal pigment epithelium (RPE). Pyridinium bisretinoid A2E is an initiator of blue-light-induced apoptosis. Photoactivation of Pyridinium bisretinoid A2E mediates autophagy and the production of reactive oxygen species. Pyridinium bisretinoid A2E can be used in the study of retinal degenerative diseases.