Aqueous outflow regulation: Optical coherence tomography implicates pressure-dependent tissue motion

Chen Xin, Ruikang K. Wang, Shaozhen Song, Tueng Shen, Joanne Wen, Elizabeth Martin, Yi Jiang, Steven Padilla, Murray Johnstone

Research output: Contribution to journalReview article

20 Scopus citations

Abstract

Glaucoma is a leading cause of blindness worldwide and results from damage to the optic nerve. Currently, intraocular pressure is the only treatable risk factor. Changes in aqueous outflow regulate pressure; regulation becomes abnormal in glaucoma. From inside the eye aqueous flows out through the trabecular meshwork into a venous sinus called Schlemm's canal, next into collector channels and finally returns to the episcleral vessels of the venous system. The location of aqueous outflow regulation is unknown. Ex vivo and in vivo studies implicate both pressure-dependent trabecular tissue motion and tissues distal to Schlemm's canal in regulation of aqueous outflow. Technologies have not previously been available to study these issues. New ex vivo imaging in human eyes identifies hinged flaps or leaflets at collector channel entrances using a high-resolution spectral domain optical coherence tomography (SD-OCT) platform. The hinged flaps open and close in synchrony with pressure-dependent trabecular meshwork motion. The SD-OCT platform images from the trabecular meshwork surface while experimentally changing transtrabecular pressure gradients. New in vivo imaging in human eyes uses a motion sensitive technology, phase-sensitive OCT to quantitate real-time pulse-dependent trabecular tissue motion as well as absence of such motion when aqueous access to the outflow system is blocked. The recent studies suggest that aqueous outflow regulation results from synchronous pressure-dependent motion involving a network of interconnected tissues including those distal to Schlemm's canal. The new imaging technologies may shed light on glaucoma mechanisms and provide guidance in the management of medical, laser and surgical decisions in glaucoma.

Original languageEnglish (US)
Pages (from-to)171-186
Number of pages16
JournalExperimental eye research
Volume158
DOIs
StatePublished - May 1 2017
Externally publishedYes

Keywords

  • Aqueous
  • Collector channels
  • Glaucoma
  • Intraocular pressure
  • Lymphatics
  • Optical coherence tomography
  • Pulsatile flow
  • Schlemm's canal
  • Trabecular meshwork

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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