Natural course of refractive errors in early onset inherited retinal diseases

Inherited retinal diseases (IRDs) are a leading cause of visual impairment in children and young adults. Individuals with IRDs have an increased prevalence of high refractive errors (REs). This study aims to characterise the natural progression of REs in patients with early onset IRDs and identify associations with specific IRDs and genes.

Retrospective cohort study of patients diagnosed with IRD's up to the age of 10 years. Data collected included demographic information, IRD type, molecular analysis (when available), and cycloplegic REs from the first and last visits.

A total of 199 patients (384 refractive measurements) were included in this study. Retinitis Pigmentosa (RP) and Achromatopsia were associated with high hypermetropia in early visits, with a decreasing RE trend over time. CNGA3, CNGB3, and CRB1 were associated with high hypermetropia, remaining high with time in CRB1. In contrast, Congenital Stationary Night Blindness (CSNB) and Blue Cone Monochromacy (BCM) demonstrated high myopia, worsening over time in CSNB, with an increasing rate in high myopia from 51.5% to 69.7% from first to last visit. Mean myopic progression in TRPM1-patients was 0.56 dioptres/year.

In patients with early onset IRDs, refractive errors have a general tendency towards lower spherical equivalents with time. TRPM1-related myopia keeps progressing during the first decade of life, warranting regular screening and consideration of early myopia control interventions to mitigate the risk of myopia-related sight-threatening complications. High hypermetropia is common in RP, staying especially high in CRB1-related cases, highlighting the importance of early screening and refractive correction.