Natural Course of Refractive Error in Congenital Stationary Night Blindness: Implications for Myopia Treatment

PURPOSE. A range of pharmacological and optical therapies are being studied and implemented in children with myopia to reduce the progression of myopia. At present, the efficacy of these myopia reduction treatments in children with underlying inherited retinal disorders (IRDs) is largely unknown. To evaluate this efficacy, it is essential to first understand the natural progression of myopia within each distinct underlying IRD. We investigated the natural course of refractive error throughout childhood in patients with congenital stationary night blindness (CSNB) of the Schubert-Bornschein type. METHODS. We retrospectively assessed a total of 295 refraction measurements in 127 patients with CSNB (48 with "complete"CSNB [CSNB1] and 79 with "incomplete"CSNB [CSNB2]) at different ages between 0 and 21 years old. None had a history of myopia control treatment. A linear mixed effects model was fitted on the data to analyze the natural course of refraction in these patients. RESULTS. The fitted model showed that refractive error in patients with CSNB increases quickly toward myopia in the first years of life. After the age of 4 years, there was a minimal progression of only -0.12 diopters (D) per year up to 15 years, after which the refraction seemed stable. All (43/43) of the patients with CSNB1 aged > 4 years were myopic and 84% (62/74) of the patients with CSNB2 aged > 4 years were myopic at the last refraction measurement. CONCLUSIONS. In general, the refractive error of children with CSNB changes minimally after the age of 4 years old. A critical approach to myopia control interventions in these children is warranted.