What causes increased intraocular pressure (IOP) in primary open-angle glaucoma (POAG)?

Updated: Mar 16, 2020
  • Author: Kristin Schmid Biggerstaff, MD; Chief Editor: Inci Irak Dersu, MD, MPH  more...
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In cases where POAG is associated with increased IOP, the cause for the elevated IOP generally is accepted to be decreased facility of aqueous outflow through the trabecular meshwork. Occurrence of this increase in resistance to flow has been suggested by multiple theories, to include the following:

  • An obstruction of the trabecular meshwork by accumulated material

  • A loss of trabecular endothelial cells

  • A reduction in trabecular pore density and size in the inner wall endothelium of the Schlemm canal

  • A loss of giant vacuoles in the inner wall endothelium of the Schlemm canal

  • A loss of normal phagocytic activity

  • Disturbance of neurologic feedback mechanisms

Other processes thought to play a role in resistance to outflow include altered corticosteroid metabolism, dysfunctional adrenergic control, abnormal immunologic processes, and oxidative damage to the meshwork.

Numerous other undetermined factors are considered to be at work in the pathogenesis of glaucoma. Basic and clinical science research continues to play a role in the search for such factors that contribute to the development and prognosis of the patient with POAG.

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