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Protrusions of the inner wall of Schlemm's canal
Abstract:
Large specific protrusions of the trabecular meshwork into Schlemm's canal (hernias) have been suggested to be the main drainage routes for aqueous humor, similar to the function of the arachnoid villi in draining the cerebrospinal fluid. My quantitative study in cynomolgus monkeys does not support such a hypothesis. The drainage routes of the aqueous humor, evaluated from the number and sizes of the pores observed by scanning electron microscopy, were as common through the hernias as through other parts of the inner wall of Schlemm's canal at different levels of intraocular pressure. The total surface of the hernias was a small percentage of the total surface of the inner wall.
Insights
Trabecular meshwork hernias are not the primary aqueous humor drainage pathway. This study found similar drainage through hernias and other Schlemm
Area of Science:
- Ophthalmology
- Fluid Dynamics
- Microscopy
Background:
- Trabecular meshwork (TM) hernias into Schlemm's canal (SC) were hypothesized as major aqueous humor (AH) outflow routes.
- This hypothesis was compared to arachnoid villi in cerebrospinal fluid drainage.
Purpose of the Study:
- To investigate the role of TM hernias in AH drainage.
- To quantitatively assess if hernias represent the primary outflow pathway.
Main Methods:
- Scanning electron microscopy (SEM) was used to examine cynomolgus monkey eyes.
- Pore number and size were analyzed in hernias and other SC inner wall regions.
- Analysis was performed at varying intraocular pressure (IOP) levels.
Main Results:
- Quantitative analysis did not support hernias as the main AH drainage route.
- AH drainage through hernias was comparable to other SC inner wall areas.
- Hernial surface area constituted a minor fraction of the total inner wall surface.
Conclusions:
- TM hernias are unlikely to be the principal pathway for AH outflow.
- Aqueous humor drainage occurs through multiple regions of the inner wall of Schlemm's canal.
- The contribution of hernias to overall AH outflow is limited.