Feeding older mice a lower glycemic index diet delays the onset of age-related, sight-threatening retinal lesions. Mice put on a higher GI diet demonstrated elevated accumulations of debris known as advanced glycation end products in the whole retina, particularly in the cells of the retinal pigment epithelium (RPE). The RPE plays a crucial role in maintaining vision and its dysfunction results in the gradual vision loss that is the hallmark of age-related macular degeneration.