Micro-Viscoelastic Properties of the Human Conventional Outflow Pathway and Their Evolution in an Early Ocular-Hypertension Model.

Primary OAG (POAG) is the second leading cause of irreversible blindness in the US and its prevalence is expected to worsen in the coming years. Major pathological changes have been attributed to the Juxtacanicular Tissue (JCT) and Inner Wall (IW) of Schlemm’s Canal (SC) within the human conventional outflow pathway. Biological tissues like the JCT/IW are viscoelastic in nature with both intra-cellular and extra-cellular mechanisms by which to store and dissipate applied forces. How these events contribute towards regulation of the local mechanobiology in the dynamic reciprocitybetween cells, their extracellular matrix (ECM), and in ultimately regulating outflow resistance, is poorly understood. Furthermore, the viscoelastic properties of the human trabecular meshwork (hTM) tissue are poorly understood. As a first step to develop more insight into the role of viscoelasticity, it was our goal to determine the localized dynamic mechanical properties of different regions of the hTM as a function of dexamethasone treatment. To explore the viscoelastic properties of the different tissue regions in the hTM comprising the hTM, we applied our co-located AFM-based rheometer/CLSM method to frontal sections of hTM under control and early ocular hypertensive conditions across a broad frequency range (1 Hz-1 kHz). We specifically considered the storage and loss moduli in the ocular pulse-relevant frequency range (1-10 Hz) and their changes across regions under dex treatment for two donors.