Gene Therapy for Retinal Degenerative Diseases: Progress, Challenges, and Future Directions.

Since long before the first approval of gene therapy for retinal disease, ocular gene therapy has captured the hopes of patients, clinicians, and scientists alike. Indeed, the retina provides a unique system for studying and treating ocular diseases, and it holds the distinction as the first tissue targeted by an approved gene therapy for inherited disorders in the United States. There are many methods for addressing genetic diseases in the eyes using a wide range of potential delivery systems and vectors. However, despite the immense progress over the last several decades, both old and new challenges remain, such as the long-term effects of treatments, immunogenicity, targeting, and manufacturing. This review provides a discussion of the history of ocular gene therapy, the various gene therapy approaches, methods to deliver a gene directly to ocular tissues (including both routes of administration and vectors), challenges to ocular gene therapy, the current clinical trial landscape, and future directions of the field.