Jean Bennett1,2 and Albert M. Maguire1,2,3 1Scheie Eye Institute at the Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania 19104, USA 2Center for Advanced Retinal and Ocular Therapeutics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA 3Division of Ophthalmology at the Children's Hospital of Philadelphia of the Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19102, USA Correspondence: jebennetpennmedicine.upenn.edu

In the 5 years following U.S. Food and Drug Administration (FDA) approval of the first gene therapy reagent approved to treat a genetic disease, voretigene neparvovec-rzyl (Luxturna), retinal disease clinics, hospital pharmacies, operating rooms, and even health insurance entities around the world have incorporated gene therapy as a standard procedure. The success of Luxturna has helped pave the way to establish a template for developing other gene therapy reagents that promise to restore sight or halt the progression of photoreceptor cell loss in both inherited and acquired retinal diseases. Here we review lessons learned from development of a gene therapy drug for RPE65 disease and how these lessons may expedite the development of additional treatments for previously untreatable blinding conditions.