Selective assessment of biomechanical properties of the lens capsule

The scientific and practical interest in studying the biomechanical characteristics of the lens capsule, on the one hand, is associated with its anatomical significance in modern microinvasive phaco surgery, and on the other hand, with investigation of the mechanisms of lens curvature changes during accommodation. Selective study of the biomechanical properties of the lens capsule aims to identify characteristics of various regions and surfaces of the capsule. Purpose. This study is a comparative analysis of age-related changes in the biomechanical properties of the anterior (AC) and posterior (PC) lens capsules in humans. Material and methods. The study analyzed 73 pairs of central fragments of the AC and PC of the lens, obtained from donor (cadaver) eyes and through anterior and posterior capsulorhexis during microinvasive phaco surgery (38 and 35 paired samples, respectively). Planned biomechanical testing followed a previously developed protocol for examining the anterior capsule, including determination of the Young’s modulus using atomic force microscopy. Results. Comparing the Young’s modulus of lens capsule samples from donor eyes and microinvasive phaco surgery revealed no significant differences in mean values, indirectly indicating minimal postmortem impact on the biomechanical properties of the capsule. General biomechanical patterns observed in the human lens capsule show the Young’s modulus (stiffness) is higher in the AC than the PC, and higher on the inner than the outer surface for both the AC and PC. Age-related changes are associated with an increase in stiffness on the outer surface and its decrease on the inner surface, more pronounced in the AC. Conclusion. The obtained results indicate the need for further investigation into the role of capsule biomechanics in age-related accommodative disorders.