Research conducted at Harvard Medical School has provided a fresh perspective on why healthy cells die in patients with retinitis pigmentosa (RP). This long-standing puzzle may now be resolved through an improved understanding of how cones receive nutrition within the retina. A comprehensive series of experiments have shown that disturbance of an insulin-associated pathway in cone photoreceptor cells can lead to their un-timely death. The finding is of major significance due to the potential to target this pathway and thereby devise a treatment strategy that could benefit an estimated 1.5 million people who lose their sight annually from RP.