OUTER RETINAL MICROCAVITATIONS IN RETINITIS PIGMENTOSA : A Novel Optical Coherence Tomography Finding Common in RP1 -Related Retinopathy.

PURPOSE: To describe a novel optical coherence tomography (OCT) finding of outer retina microcavitations in RP1 -related retinopathy and other retinal degenerations. METHODS: Medical charts and OCT images of 28 patients with either autosomal dominant retinitis pigmentosa or autosomal recessive retinitis pigmentosa RP1 -related retinopathy were reviewed. Outer retina microcavitations were defined as hyporeflective OCT structures of at least 30 µ m in diameter between the ellipsoid zone and retinal pigment epithelium. Comparison was made based on the following metrics: (1) functional measures including best-corrected visual acuity and color discrimination errors on D-15 test; and (2) structural measures, including central subfield, average macular thickness, and preserved transfoveal ellipsoid zone width. Mann-Whitney tests were used for comparisons with significance set at P < 0.05. The specificity of microcavitations for RP1 -related retinopathy was estimated against 26 patients with non- RP1 retinitis pigmentosa. RESULTS: Among 15 included patients, microcavitations were found in at least one eye of all patients with arRP and 7/12 (58%) of patients with adRP. Patients with adRP and microcavitations were older at the time of examination (51 vs. 43 years of age; P = 0.04) and their eyes demonstrated worse best-corrected visual acuity (0.09 vs. 0 logMAR; P = 0.008), reduced central subfield (256 vs. 293 µ m; P = 0.01), average macular thickness (241 vs. 270 µ m; P = 0.02), and shorter transfoveal ellipsoid zone widths (1.67 vs. 4.98 mm; P < 0.0001). The finding of microcavitations showed a specificity of 0.92 for RP1 -related retinopathy. CONCLUSION: A novel OCT finding of outer retina microcavitations was commonly observed in patients with RP1 -related retinopathy. Eyes with outer retinal OCT microcavitations had worse visual function and more affected central retinal structure.

RPGR: Deep Phenotyping and Genetic Characterization With Findings Specific to the 3'-end of ORF15.

Purpose: To describe a group of patients with retinitis pigmentosa GTPase regulator (RPGR)-related retinopathy with a tapetal-like retinal sheen and corresponding changes in the reflectivity of the ellipsoid zone on optical coherence tomography (OCT) imaging. Methods: A retrospective case series of 66 patients with a disease-causing variant in RPGR was performed. An expert examiner, masked to patient demographics, clinical evaluations, and specific RPGR variant, analyzed color fundus photographs for the presence of a tapetal-like retinal sheen and assessed OCT images for the presence of an abnormally broad hyper-reflective band in the outer retina. Longitudinal reflectivity profiles were generated and compared with healthy controls. Results: Twelve patients (18.2%) had a retinal sheen on color images that cosegregated with an abnormally broad hyper-reflective ellipsoid zone band on OCT imaging. Three-fourths of these patients were male, had a cone-rod dystrophy, and had pathogenic RPGR variants located toward the 3'-end of ORF15. This group had a different longitudinal reflectivity profile signature compared with controls. After a period of prolonged dark adaptation, the abnormal hyper-reflective band on OCT became less apparent, and the outer retinal layers adopted a more normal appearance. Conclusions: RPGR-related retinopathy should be considered for males presenting with retinal sheen, abnormal ellipsoid zone hyper-reflectivity, and cone or cone-rod dysfunction on ERG, and pursued with molecular testing. Our results have implications for understanding the role of the C-terminal domain encoded by RPGR ORF15 in the phototransduction cascade. Further, the findings may be important to incorporate into both inclusion criteria and outcome measure developments in future RPGR-related cone or cone-rod dystrophy clinical trials.