Associations between corneal biomechanical parameters and retinal superficial vessel density in young adults with varying myopia severity: a cross-sectional study

AimTo evaluate associations between corneal biomechanical parameters and superficial retinal vessel density (SVD) in young adults with varying myopia severity and determine whether these associations differ myopia severity groups.MethodsThis cross-sectional study included 167 participants contributing 320 eyes (93 low-, 125 moderate-, and 102 high-myopia eyes). Corneal biomechanical parameters were assessed using Corneal Visualization Scheimpflug Technology (Corvis ST), and macular and peripapillary SVD using optical coherence tomography angiography (OCTA). Eye-level analyses used linear mixed-effects models (LMMs) with participant identity as a random intercept to account for inter-eye correlation. Association models were adjusted for axial length, age, sex, and biomechanically corrected intraocular pressure (bIOP). Biomechanical parameter × myopia severity interactions were tested to assess between-group differences in associations.ResultsPeak distance (PD), stress-strain index (SSI), stiffness parameter at first applanation (SP-A1), and Ambrosio relational thickness-horizontal (ARTh) differed significantly among myopia groups (all P < 0.05). Macular SVD differed in the inner nasal (IN) and outer nasal (ON) regions, while peripapillary SVD differed in the IN, inner temporal (IT), outer superior (OS), outer inferior (OI), ON, and outer temporal (OT) regions (all P < 0.05). After covariate adjustment, several corneal biomechanical parameters remained associated with regional SVD. IRA × myopia severity interactions were significant for central, II, IN, IT, and OT macular SVD (all P for interaction < 0.05), while PD also showed a significant interaction with myopia severity for central SVD (P for interaction = 0.023). For peripapillary SVD, a significant IRA × myopia severity interaction was observed in the OS region (P for interaction = 0.015).ConclusionCorneal biomechanical parameters and retinal SVD showed regional differences across myopia severity groups. After accounting for inter-eye correlation and relevant covariates, selected biomechanical parameters were associated with regional SVD, and some associations differed by myopia severity. These findings suggest a potential relationship between anterior segment biomechanical characteristics and retinal microvascular alterations; however, the cross-sectional design precludes causal or longitudinal interpretation.