OUTER RETINAL MICROCAVITATIONS IN RETINITIS PIGMENTOSA

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 (adRP) or recessive (arRP) RP1 -related retinopathy were reviewed. Outer retina microcavitations were defined as hypo-reflective OCT structures of at least 30μm in diameter between the ellipsoid zone (EZ) and retinal pigment epithelium. Comparison was made based on the following metrics: (i) functional measures including best-corrected visual acuity (BCVA) and color discrimination errors on D-15 test; and (ii) structural measures, including central subfield (CSF), average macular thickness (AMT), and preserved transfoveal EZ 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 RP. RESULTS. Among 15 included patients, microcavitations were found in at least one eye of all arR patients and 7/12 (58%) of adR patients. Patients with adR and microcavitations were older at the time of examination (51 vs. 43 years of age; p=0.04) and their eyes demonstrated worse BCVA (0.09 vs. 0 logMAR; p=0.008), reduced CSF (256 vs. 293μm; p=0.01), AMT (241 vs. 270μm; p=0.02) and shorter transfoveal EZ widths (1.67 vs. 4.98mm; 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.