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Review
. 2022 Jun;100(4):e881-e890.
doi: 10.1111/aos.15027. Epub 2021 Sep 13.

Schlemm's canal: the outflow 'vessel'

Katarzyna Lewczuk  1 , Joanna Jabłońska  1 , Joanna Konopińska  2 , Zofia Mariak  2 , Marek Rękas  1
Affiliations
Review

Schlemm's canal: the outflow 'vessel'

Katarzyna Lewczuk et al. Acta Ophthalmol. 2022 Jun.

Abstract

In a healthy eye, the aqueous humour (AH) flows via the ciliary body and trabecular meshwork into the collector channels, which carry it to the episcleral veins. In glaucoma, a heterogeneous group of eye disorders affecting approximately 60 million individuals worldwide, the juxtacanalicular meshwork offers greater resistance to the outflow of the AH, leading to an increase in outflow resistance that gradually results in elevated intraocular pressure (IOP). The present review comprehensively covers the morphology of Schlemm's canal (SC) and AH pathways. The path of the AH from the anterior chamber through the trabeculum into suprascleral and conjunctival veins via collector channels is described, and the role of SC in the development of glaucoma and outflow resistance is discussed. Finally, channelography is presented as a precise method of assessing the conventional drainage pathway and facilitating localization of an uncollapsed collector and aqueous veins. Attention is also given to the relationship between aqueous and episcleral veins and heartbeat. Possible directions of future research are proposed.

Keywords: Schlemm's canal; aqueous humour; channelography; conventional drainage pathway; glaucoma; outflow resistance.

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Figures

Fig. 1
Fig. 1
The anatomy of Schlemm’s canal.
Fig. 2
Fig. 2
The aqueous vein visible in channelography.
Fig. 3
Fig. 3
SC – (Schlemm’s canal) and CC (collector channel) visible on ultrasound biomicroscopy images.
Fig. 4
Fig. 4
Aqueous veins.
Fig. 5
Fig. 5
Episcleral veins.
See this image and copyright information in PMC

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