Analysis of macular curvature in normal eyes using swept-source optical coherence tomography

Purpose: To evaluate macular shape in normal eyes using swept-source optical coherence tomography (SS-OCT). Study design: Retrospective cross-sectional study. Methods: We retrospectively evaluated 77 normal eyes of 48 subjects. Curvature of retinal pitment epithelium (RPE) and choroid/scleral interface (CSI) was measured in vertical and horizontal SS-OCT 16-mm scanned images. After correcting the optical distortion of OCT images, curvatures of superior, central, and inferior sectors in the vertical scan, and temporal, central, and nasal sectors in the horizontal scan (each 4-mm length) were compared. Factors associated with overall RPE and CSI curvatures were investigated. Results: RPE and CSI curvatures of superior, central, and inferior sectors in the vertical scan were 16.6±3.1, 13.8±2.1, 17.7±3.2 and 17.8±3.0, 13.8±3.3, 18.4±3.3 (×10⁻⁵ μm⁻¹), respectively. Central curvature was significantly flatter than superior and inferior curvatures in both RPE and CSI (all P<0.001). The RPE and CSI curvatures of temporal, central, and nasal sectors in the horizontal scan were 17.2±2.3, 15.2±2.5, 18.8±2.7 and 18.3±2.7, 16.7±2.9,14.4±2.9 (×10⁻⁵ μm⁻¹), respectively. While central curvature was significantly flatter than nasal and temporal curvatures in RPE (P<0.001 and P=0.025), nasal curvature was significantly flatter than central and temporal curvatures (P=0.027 and P<0.001) in CSI. Overall CSI curvature was significantly associated with axial length (AL) (P<0.001), whereas overall RPE curvature was significantly associated with overall CSI curvature (P<0.001), choroidal thickness (P<0.001), and AL (P=0.038) Conclusions: This study revealed that RPE curvature is associated with CSI curvature, choroidal thickness, and AL, suggesting that choroidal and scleral structures affect macular RPE curvature.