Elastic modulus determination of normal and glaucomatous human trabecular meshwork

Area of Science:

• Ocular biomechanics
• Glaucoma research
• Biophysics of the eye

Background:

• Elevated intraocular pressure (IOP) is a primary risk factor for glaucoma.
• The trabecular meshwork (HTM) and Schlemm's canal (SC) are crucial for aqueous humor outflow and IOP regulation.
• Increased stiffness of the HTM may contribute to elevated IOP in glaucoma.

Purpose of the Study:

• To compare the stiffness of normal and glaucomatous human trabecular meshwork (HTM).
• To develop a mathematical model to assess the impact of HTM stiffness on aqueous humor outflow dynamics.
• To investigate the role of HTM biophysical properties in glaucoma.

Main Methods:

• Atomic force microscopy (AFM) was employed to measure the elastic modulus of normal and glaucomatous HTM.
• A computational model simulating the juxtacanalicular layer of the HTM as a porous, flexible membrane was developed.
• Flow resistance was analyzed in relation to varying HTM stiffness parameters.

Main Results:

• Glaucomatous HTM exhibited a significantly higher elastic modulus (mean = 80.8 kPa) compared to normal HTM (mean = 4.0 kPa).
• Regional variations in stiffness were observed within glaucomatous HTM samples.
• Mathematical modeling indicated that increased HTM stiffness leads to greater resistance to aqueous humor flow.

Conclusions:

• The study confirms significantly increased stiffness in glaucomatous HTM compared to normal tissue.
• Increased HTM stiffness demonstrably impairs outflow facility, as supported by modeling.
• Alterations in the mechanical properties of the HTM are implicated in the pathogenesis of glaucoma.