Measurements of OCTA Complement OCT for Diagnosing Early Primary Open Angle Glaucoma

Abstract Purpose To compare measurements of global and regional circumpapillary capillary density (cpCD) with retinal nerve fiber layer (RNFL) thickness, and characterize their relationship with visual function in early primary open-angle glaucoma (POAG). Design Cross-sectional study Participants Eighty healthy eyes, 64 pre-perimetric, and 184 mild POAG eyes from the Diagnostic Innovations in Glaucoma Study. Methods Global and regional RNFL thickness and cpCD measurements were obtained using optical coherence tomography (OCT) and OCT angiography (OCTA). For direct comparison at the individual and diagnostic group level, RNFL thickness and capillary density values were converted to a normalized relative loss scale. Main Outcome Measures RNFL thickness and cpCD normalized loss at the individual level and diagnostic group. Global and regional areas under the receiver operating characteristic curve (AUROC) for RNFL thickness and cpCD to detect pre-perimetric glaucoma and glaucoma. R-squared for the strength of associations between RNFL thickness-function and capillary density-function in diagnostic groups. Results Both global and regional RNFL thickness and cpCD decreased progressively with increasing glaucoma severity (P Conclusions Associations between capillary density and visual function were found in the regions known to be at highest risk for damage in pre-perimetric glaucoma eyes and all regions of mild glaucoma eyes. In early glaucoma, capillary density loss was more pronounced than RNFL thickness loss. Individual characteristics influence the relative magnitudes of capillary density loss compared to RNFL thickness loss. RNFL thickness and microvascular assessments are complementary and yield valuable information for the detection of early damages seen in POAG.