Schlemm's canal and primary open angle glaucoma: correlation between Schlemm's canal dimensions and outflow facility

Area of Science:

• Ophthalmology
• Anatomy
• Glaucoma Research

Background:

• Intraocular pressure regulation is crucial for ocular health.
• Schlemm's canal (SC) plays a vital role in aqueous humor outflow.
• Morphological changes in SC are implicated in glaucoma pathogenesis.

Purpose of the Study:

• To investigate the relationship between outflow facility and Schlemm's canal morphometry.
• To compare SC dimensions in normal versus primary open-angle glaucoma (POAG) eyes.
• To quantify the contribution of SC morphometry to reduced outflow facility in POAG.

Main Methods:

• Outflow facility was measured in normal and POAG human eyes.
• Morphometric analysis of Schlemm's canal (SC) cross-sectional area, perimeter, and inner wall length was performed.
• SC sections from eight quadrants per eye were analyzed using a morphometric system.

Main Results:

• A significant positive correlation was observed between outflow facility and SC cross-sectional area (P < 0.01).
• POAG eyes exhibited significantly smaller SC cross-sectional area, perimeter, and inner wall length compared to normal eyes.
• Reduced SC inner wall length alone accounted for 41-55% of the outflow facility difference between normal and POAG eyes.

Conclusions:

• Glaucomatous human eyes demonstrate significantly reduced Schlemm's canal dimensions.
• These SC dimensional deficits are strongly associated with decreased outflow facility in POAG.
• Reduced SC morphometry is a significant factor contributing to impaired aqueous humor drainage in glaucoma.