On influence of sulfated glycosaminoglycans on tensile properties of posterior sclera

Abstract

The biomechanical behavior of sclera is conferred by the composition and structure of its extracellular matrix, which is mainly composed of collagen fibers and sulfated glycosaminoglycans (GAGs). Pathological conditions and visual disorders such as glaucoma and myopia could cause significant changes to the mechanical properties and GAG content of sclera. There exists sufficient evidence for the contribution of collagen fibers to the scleral biomechanics; however, possible mechanical roles of GAGs are not fully known. The primary objective of this work was to examine the mechanical function of GAGs through characterizing their effects on the scleral tensile response. For this purpose, chondroitinase ABC was used to deplete GAGs from posterior porcine scleral samples. Comprehensive biochemical and histological analyses were then performed to confirm and quantify GAG removal. Stress-controlled tensile tests with preconditioning were conducted in order to characterize the viscoelastic tensile behavior of treated and untreated specimens. It was found that the enzyme treatment caused a significant thickness reduction but it did not cause any significant change in the tensile properties of sclera. Overall, the findings of this study suggested that alternations in the GAG content of posterior scleral tissue are not important to tensile properties of sclera that are measured by stress-controlled experiments.