Biomechanical responses and scleral reinforcement across staphyloma subtypes in pathologic myopia: a finite element analysis

Objective Posterior scleral staphyloma (PSS) is a common complication of pathologic myopia and may lead to deformation of posterior pole structures, including macula and lamina cribrosa (LC). Different types of PSS exhibit distinct structural features and corresponding patterns of fundus damage. Prior studies have defined PSS morphological classification and its association with fundus lesions, yet the biomechanical mechanisms of subtype-specific damage and quantitative evaluation of posterior scleral reinforcement (PSR) remain unaddressed. Therefore, this study explored posterior pole biomechanical responses in PSS and PSR efficacy to guide clinical management. Methods Whole-eye finite element models were established incorporating five Curtin-classified PSS subtypes and three axial lengths. Key posterior pole biomechanical parameters related to lamina cribrosa displacement and macular strain were extracted. PSR was then simulated using the reinforcing strip with varied elastic moduli to compare pre- and post-operative mechanical responses. Results PSS subtype and staphyloma depth-radius morphological combinations influenced biomechanical responses of posterior pole structures. Type I (wide macular) PSS demonstrated the largest LC displacements, with mean LC_X_DistMean of 0.0215 ± 0.0133 mm and LC_Y_DistMean of 0.0188 ± 0.0138 mm. HSR_RM_0.04 was lower in the PSR models (from 19.45% to 3.58%), indicating reduced macular high-strain exposure. Higher strip modulus further decreased HSR_RM_0.04 across all five PSS subtypes. Conclusion PSS subtype-specific geometries showed the largest effect within the tested parameter ranges, while the depth-radius configuration accounted for subtype-specific variations in macular strain patterns. PSR simulations indicated reduced IOP-driven HSR_RM_0.04, enhanced by higher strip modulus with the strip configuration used in this study. These findings support morphology-tailored, in silico comparisons within static idealized models and warrant prospective clinical validation.