Corneoscleral Morphology in Keratoconus and Its Association With Corneal Tomography and Biomechanics

Purpose: To characterize corneoscleral morphology in keratoconus versus normal eyes via anterior segment optical coherence tomography (AS-OCT) and investigate its relationship with Scheimpflug-based corneal tomography and corneal biomechanics. Methods: This cross-sectional study included 43 keratoconus and 74 control eyes. AS-OCT imaging was conducted across superior, inferior, nasal, and temporal meridians at the corneoscleral limbus. Chord-based scleral and corneal curvature were assessed at 5 mm (SclCurv5, CorCurv5) and at 2.5 mm (SclCurv2.5, CorCurv2.5) from the scleral spur. The corneoscleral junction angle (CSJA) was also analyzed. Group and meridian differences were evaluated, and associations with corneal tomography (Pentacam) and biomechanics (Corvis ST) were explored. Results: Keratoconic eyes exhibited a distinct corneoscleral architectural pattern compared to controls, characterized by greater vertical asymmetry in SclCurv5 and CorCurv5, as well as flatter inferior SclCurv2.5 and flatter inferior and temporal CorCurv5 (all P < 0.05). Within the keratoconus group, a larger superior CSJA was associated with a more favorable profile of corneal tomographic and biomechanical parameters, including lower maximum keratometry, exp(β) = 0.95, P = 0.002; a lower topographic keratoconus classification grade, exp(β) = 0.54, P = 0.038; and greater thickness-profile-integrated stiffness, as measured by Ambrósio's relational thickness horizontal, exp(β) = 1.10, P = 0.027. Conclusions: Keratoconus involves significant alterations in corneoscleral architecture beyond the cornea itself. A larger superior CSJA emerged as a significant independent predictor of a milder disease phenotype among keratoconus patients. Translational Relevance: A larger superior CSJA may indicate a slower disease progression, aiding in personalized monitoring and management planning.