Smaller Optic Discs Show Higher Macular Flow Density: An Optical Coherence Tomography Angiography Study

Background/Objectives: This study aimed to investigate the correlation between macular flow density (FD) as well as foveal avascular zone (FAZ) characteristics and optic disc size, quantified by Bruch's membrane opening area (BMOA). In addition, potential differences in FD and FAZ parameters among optic disc size cohorts were evaluated. Methods: In this retrospective, single-centre study, 151 eyes from 151 healthy participants examined at the University Hospital Münster, Germany, were included. Each subject underwent macular and optic disc optical coherence tomography angiography (OCT-A). Rank correlation coefficients for clustered data were computed to assess associations between FD values and BMOA. Further analyses compared FD and FAZ parameters among three optic disc size groups based on their quantiles. Results: Statistical analysis revealed a significant negative correlation between FD in several macular subsectors and BMOA. When stratified by optic disc size, FD in the superficial capillary plexus (SCP) was significantly higher in eyes with the smallest discs compared with intermediate ones, and FD in the deep capillary plexus (DCP) was significantly higher in intermediate discs compared with the largest group. Additionally, both SCP and DCP showed higher absolute FD values in eyes with the smallest optic discs compared with those with the largest. No significant group differences were detected for foveal FD, FAZ area, or FAZ perimeter. Conclusions: This study contributes to normative OCT-A data by incorporating optic disc size as a variable. While FAZ parameters appeared independent of BMOA, eyes with smaller optic discs demonstrated higher FD values in both SCP and DCP.