The Importance of Natural History Studies in Inherited Retinal Diseases.

Natural history studies of inherited retinal diseases (IRDs) play a critical role in the design and implementation of treatment trials. Study objectives ideally encompass (1) understanding the time course and pattern of disease progression, (2) within genotypic and phenotypic subtypes of patient populations, and (3) characterizing a range of measures of vision function, retinal structure, and functional vision that may serve as endpoints. In rare disease, data quality standards are paramount to optimizing smaller sample sizes, including a prospective, standardized, and longitudinal approach to data collection. Multicenter studies additionally facilitate strength in numbers and generalizability, and multidisciplinary collaboration ensures a holistic approach to study design and knowledge-building. Dissemination of natural history study results, data sets, and lessons learned will stimulate further innovation and progress in IRD therapeutic research, including setting up future trial designs for their best chance of success.