Peripapillary Choroidal Vascularity Index in Glaucoma-A Comparison Between Spectral-Domain OCT and OCT Angiography

To compare the choroidal vascularity index (CVI) determined by spectral-domain optical coherence tomography (OCT) between eyes with and without parapapillary deep-layer microvasculature dropout (MvD_P) assessed by OCT angiography in glaucomatous eyes. A total of 100 open-angle glaucoma patients with and without MvD_P (50 eyes of 50 patients in each group) matched by age and visual field mean deviation were included. Total choroidal area (TCA) and CVI were measured by image binarization of spectral-domain OCT B-scans in order to assess the choroidal vasculature outside β-zone parapapillary atrophy (βPPA) at a 3.5-mm distance from the Bruch's membrane opening center. MvD_P was determined by OCT angiography as a deep-layer microvasculature dropout within βPPA. Global and sectoral (six 60° sectors) TCA and CVI were compared between eyes with and without MvD_P. The CVIs of eyes with MvD_P were significantly lower than those without MvD_P, globally (P = 0.010) as well as in the inferotemporal (TI) (P = 0.003), temporal (P = 0.009), and nasal (P = 0.048) sectors. Eyes with MvD_P, of which the largest portion was located only in the TI sector (n = 33), had significantly lower CVI than those without MvD_P in the corresponding TI and temporal sectors (P < 0.05 for all), whereas TCA did not differ in any areas. Eyes with MvD_P had significantly lower CVIs than did those without MvD_P. Furthermore, CVI reduction was spatially correlated with MvD_P. Further studies investigating the influence of MvD_P on the choroidal vasculature outside βPPA are warranted.