Effects of Schlemm's Canal Expansion: Biomechanics and MIGS Implications

To evaluate the change of biomechanical properties of the trabecular meshwork (TM) and configuration of collector channels (CC) by high-resolution optical coherence tomography (HR-OCT) induced by Schlemm's canal (SC) dilation.

The anterior segments of two human eyes were divided into four quadrants. One end of a specially designed cannula was placed in SC and the other end connected to a perfusion reservoir. HR-OCT provided three-dimensional (3D) volumetric and two-dimensional (2D) cross-sectional imaging permitting assessment of the biomechanical properties of the TM. A large fluid bolus was introduced into SC. Same-sample, pre and post deformation and disruption of SC and CC lumen areas were analyzed.

Morphologic 3D reconstructions documented pressure-dependent changes in lumen dimension of SC, CC, and circumferential intrascleral channels. 2D imaging established volumetric stress-strain curves (elastance curves) of the TM in quadrants. The curves of TM elastance shift to the right with an increase in pressure-dependent steady-state SC area. After a bolus disruption, the SC area increased, while the CC area decreased.

Our experimental setup permits the study of the biomechanical properties of TM by examining elastance, which differs segmentally and is altered by mechanical expansion of SC by a fluid bolus. The study may shed light on mechanisms of intraocular pressure control of some glaucoma surgery.