Association between refractive status and quantitative corneal subbasal nerve plexus parameters in young adults

To evaluate the association between refractive status and quantitative corneal subbasal nerve plexus (SBNP) parameters in healthy young adults, and to explore their relationships with ocular biometric measures. Methods: This cross-sectional study included 264 healthy participants (one righteye each, 18–38 years). Eyes were grouped by spherical equivalent (SE) into hyperopia, emmetropia, low, moderate, and high myopia. In vivo corneal confocal microscopy was performed, and SBNP parameters were quantified using automated analysis (ACCMetrics v3): corneal nerve fiber density (CNFD), corneal nerve fiber length (CNFL), corneal nerve branch density (CNBD), corneal total branch density (CTBD), and corneal nerve fiber width (CNFW). Group differences were tested, and associations with SE, axial length (AL), central corneal thickness (CCT), and corneal curvature were assessed using Spearman correlation. Results: CNFD, CNFL, and CNBD differed significantly among refractive groups and showed a decreasing trend with increasing myopia, whereas CTBD did not show a clear between-group difference and CNFW did not differ significantly between groups. SE was positively associated with CNFD, CNFL, and CNBD (all P < 0.001). The association between SE and CTBD was statistically significant but weak (r ≈ 0.12), suggesting limited clinical relevance.AL was negatively correlated with CNFD, CNFL, CNBD, and CTBD (all P < 0. 05). CCT showed no significant association with SBNP parameters, and corneal curvature demonstrated limited association. Conclusions: In healthy young adults, greater myopia and longer axial length are associated with lower density-, length-, and branching-related SBNP metrics on confocal microscopy. These data provide clinically relevant baseline reference information for refractive-surgery candidates and may aid preoperative counseling and ocular surface evaluation. Longitudinal studies are warranted to clarify temporal relationships.