" The retina is an extension of the brain- it’s part of our central nervous system. The cells that form the retina migrate off of the same cluster of cells that form the brain early in embryonic development (same tissue). We look at the retina for brain diseases like Alzheimer’s because it’s exposed tissue that can be looked at under microscopic detail without any harm, or any invasive procedures. It’s a rare opportunity to look at actual nervous system tissue like brain tissue for clues for Alzheimer’s at a potential cost that’s much lower than the cost of brain scans. "