Anterior Corneal Higher-Order Aberrations and Quantitative Macular OCT Angiography Metrics in Healthy Eyes: A Cross-Sectional Study.

Abstract

Purpose: To investigate whether anterior corneal higher‑order aberrations (HOA) influence the measurement of macular optical coherence tomography angiography (OCTA) features, including foveal avascular zone (FAZ) parameters and macular vessel density (VD) across different retinal layers.

Methods: We conducted a single‑center, retrospective, cross-sectional study of 110 healthy eyes of 110 patients. Anterior corneal HOA were measured over a fixed 6-mm zone by Scheimpflug-Placido corneal topography. Macular OCTA (6 × 6 mm) provided VD in the superficial (SCP) and deep (DCP) capillary plexuses, and FAZ area, perimeter, and circularity on the full inner retinal slab. Signal strength index (SSI), axial length, tear‑break‑up time, scotopic pupil diameter, age, and sex were also recorded. Each OCTA parameter was then regressed on total HOA by multivariable linear regression with adjustment for these covariates, and an exploratory mediation analysis partitioned the association into signal‑strength‑mediated and non‑mediated components.

Results: Corneal total HOA was inversely associated with SCP whole‑image VD (standardized β = ‑0.41, partial r = ‑0.56) and, more strongly, with DCP whole‑image VD (β = ‑0.50, partial r = ‑0.62; both p < .001). Only 35% of the association was mediated by SSI. Absolute VD differences between the lowest and highest HOA tertiles were 3.60% for SCP and 3.94% for DCP. FAZ area, perimeter, and circularity showed no association with corneal HOA (all |β| <0.07; p > .50).

Conclusions: Higher anterior corneal HOA were associated with lower measured macular VD, and the device SSI explained only part of this. FAZ metrics were unaffected. No independent reference measurement of retinal perfusion was available, so whether this reflects a measurement effect or a true perfusion difference remains undetermined.