Retinitis Pigmentosa (RP), a genetically inherited disease that affects the photoreceptors at the back of the eye, leads to blindness. Kristin Macdonald was told she had RP at age 31 - a diagnosis that vaulted her into advocacy. She shares her story of living with blindness, participating in clinical trials, and hope for the future. Series: "Stem Cell Channel" [Health and Medicine] [Science] [Show ID: 36433]