Analysis of In Vivo Sclera Impact on the Biomechanics of Myopic Eyes.

The purpose of this study was to evaluate the relationship between in vivo scleral thickness and biomechanical properties in eyes with myopia and to examine the association between in vivo sclera and the severity of myopia. This prospective case series included 101 eyes from 101 patients with myopia. Corneal biomechanical parameters and anterior scleral images were acquired using the Corvis ST and anterior segment optical coherence tomography (AS-OCT), respectively. Anterior scleral thickness (AST) was measured at the scleral spur (AST0), and at 1 mm (AST1), 2 mm (AST2), and 3 mm (AST3) along the nasal (NAST) and temporal (TAST) regions. The correlations among corneal biomechanical parameters, AST, axial length (AL), and spherical equivalent refraction (SER) were analyzed after adjusting for confounding factors. The scleral spur (AST0) was thicker than the other regions (P < 0.0001). After adjusting for confounding factors, the corneal biomechanical parameters, the stiffness parameter at highest concavity (SP-HC) was significantly related to scleral thickness (P < 0.05, rNAST0 = 0.369, rNAST1 = 0.236, rNAST2 = 0.217, and rTAST0 = 0.480). SP-HC (r = 0.223) and peak distance (r = -0.259) were significantly related to SER (P < 0.05). Scleral thickness, particularly at the scleral spur, is an important factor influencing in vivo biomechanics of myopic eyes. The stiffness parameter SP-HC showed the strongest correlation with in vivo AST, potentially reflecting scleral biomechanical properties. SP-HC decreased significantly with increasing myopia, suggesting that weaker scleral biomechanics may be a risk factor for myopia progression. In vivo stiffness parameter SP-HC may indirectly quantify scleral properties and serve as a high-risk biomechanical indicator to evaluate myopia progression.