Background: To evaluate choroidal vascular changes, including choriocapillaris (CC) and middle/large choroidal vessels, in retinitis pigmentosa (RP) patients using wide-angle optical coherence tomography angiography (OCTA) and to determine whether changes in the choroidal vascularity have a relationship with visual function and retinal structural changes.
Methods: 34 patients with a confirmed diagnosis of RP and 48 controls were recruited. All patients underwent detailed ophthalmologic and imaging examinations, including two types of OCTA (Optovue, 3 × 3 mm, 6 × 6 mm; VG-200, 12 × 12 mm). CC defects were defined according to the choroidal vascular structure in five degrees. To evaluate middle and large choroidal vascular changes, the choroidal vascularity index (CVI), which was the luminance volume to the total choroidal volume, was used.
Results: Defects of choroidal vascularity of RP eyes were detected in comparison to control eyes. The defects were observed in the CC layer with a concentric or lobular pattern at different degrees. CVI, which was used to reflect middle/large choroidal vascularity, decreased in the perifoveal, pararetinal and periretinal regions in the RP eyes. CC defects degree were correlated with the BCVA (p = 0.001, r = - 0.556), the Humphrey indexes (mean deviation, MD, p < 0.001, r = - 0.673; PVF, p = 0.003, r = - 0.639; 10° mean sensitivity, 10° MS, p = 0.002, r = - 0.651) and microperimetry index (mean sensitivity, MS, p < 0.001, r = - 0.807). The preserved CC area (mean value: 28.65 ± 12.50 mm2) was negatively correlated with MS measured by microperimetry (p = 0.005, r = - 0.449). Ordinary regression analysis revealed that the CC defect degree was associated with the CVI of perifovea (p = 0.002, 95% CI: - 102.14 to - 24.01), the EZ length (p = 0.006, 95% CI: - 0.006 to - 0.001) and the VAD (vascular area density) of the DCP (deep capillary plexus) in the fovea (p = 0.022, 95% CI: 0.038-0.478). No correlations were detected between BCVA and CVI in any retinal regions. No correlations were found between the CVI and the VAD in any retinal regions.
Conclusion: The choroidal vascularity was widely defected in RP. Choriocapillaris and middle/large choroidal vascularity defects were correlated with each other. Visual function and retinal structural changes were found to be associated with choriocapillaris defects but not with middle/large choroidal vascular defects.
Keywords: Choriocapillaris;large-angle OCT angiography; Choroidal vascularity; Choroidal vascularity index; Retinitis pigmentosa.