CRB1-Associated Retinal Dystrophies: A Prospective Natural History Study in Anticipation of Future Clinical Trials
Xuan‐Thanh‐An Nguyen, Mays Talib, Mary J. van Schooneveld, Jan Wijnholds, Maria M. van Genderen, Nicoline E. Schalij‐Delfos, Caroline C. W. Klaver, Herman E. Talsma, Marta Fiocco, Ralph J. Florijn, Jacoline B. ten Brink, Frans P.M. Cremers, Magda A. Meester‐Smoor, L. Ingeborgh van den Born, Carel B. Hoyng, Alberta A. H. J. Thiadens, Arthur A. Bergen, Camiel J.F. Boon
Abstract
PURPOSE: To investigate the natural disease course of retinal dystrophies associated with crumbs cell polarity complex component 1 (CRB1) and identify clinical end points for future clinical trials. DESIGN: Single-center, prospective case series. METHODS: An investigator-initiated nationwide collaborative study that included 22 patients with CRB1-associated retinal dystrophies. Patients underwent ophthalmic assessment at baseline and 2 years after baseline. Clinical examination included best-corrected visual acuity (BCVA) using Early Treatment Diabetic Retinopathy Study charts, Goldmann kinetic perimetry (V4e isopter seeing retinal areas), microperimetry, full-field electroretinography, full-field stimulus threshold (FST), fundus photography, spectral-domain optical coherence tomography, and fundus autofluorescence imaging. RESULTS: Based on genetic, clinical, and electrophysiological data, patients were diagnosed with retinitis pigmentosa (19 [86%]), cone-rod dystrophy (2 [9%]), or isolated macular dystrophy (1 [5%]). Analysis of the entire cohort at 2 years showed no significant changes in BCVA (P = .069) or V4e isopter seeing retinal areas (P = .616), although signs of clinical progression were present in individual patients. Macular sensitivity measured on microperimetry revealed a significant reduction at the 2-year follow-up (P < .001). FST responses were measurable in patients with nonrecordable electroretinograms. On average, FST responses remained stable during follow-up. CONCLUSION: In CRB1-associated retinal dystrophies, visual acuity and visual field measures remain relatively stable over the course of 2 years. Microperimetry showed a significant decrease in retinal sensitivity during follow-up and may be a more sensitive progression marker. Retinal sensitivity on microperimetry may serve as a functional clinical end point in future human treatment trials for CRB1-associated retinal dystrophies.