Clinical/Demographic Functional Testing and Multimodal Imaging Differences between Genetically Solved and Unsolved Retinitis Pigmentosa

Introduction: The purpose of this study was to compare clinical/demographic functional testing and multimodal imaging features between genetically solved and genetically unsolved nonsyndromic retinitis pigmentosa (nsRP) patients. Methods: A cross-sectional study was conducted at an inherited retinal dystrophies reference center. Consecutive patients with nsRP and available genetic testing results performed between 2018 and 2020 were included. Genetic testing was clinically oriented, and variants were classified according to the American College of Medical Genetics and Genomics. Only class IV or V variants were considered disease-causing. Clinical/demographic, functional, and imaging features were compared between genetically unsolved (G1) and genetically solved (G2) patients. Results: A total of 175 patients (146 families) were included: 68 patients (59 families) in G1 and 107 patients (87 families) in G2. First symptoms <25 years, consanguinity, evidence for a particular inheritance pattern, and the absence of indicators for phenocopies were significantly more prevalent in G2. No significant differences were observed on best-corrected visual acuity. The visual field index and mean central retinal layer thickness were significantly higher in G1. The frequency of atypical features on multimodal imaging did not differ between groups. Conclusion: Individual clinical/demographic functional testing and multimodal imaging features should be considered when counseling patients about the probability of identifying disease-causing variants.