Anatomy of the conventional aqueous outflow pathway
David L. Swain
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A better understanding of the anatomy of the outflow pathways can be useful in knowing how each class of minimally invasive glaucoma surgery (MIGS) devices works. This article reviews the anatomy of the aqueous drainage pathways, emphasizing the trabecular meshwork. Experimental evidence of the location of the major sources of outflow resistance in this pathway and their contribution to glaucoma pathogenesis are discussed. The segmental outflow pattern around the circumference of the eye, structural differences in high- and non-flow areas, and morphological changes that are responsible for the reduction of effective filtration area (EFA) with increased intraocular pressure (IOP) and glaucoma are also discussed. Lowering IOP can be achieved by medical and surgical treatments, through increasing EFAs in the trabecular meshwork and in the episcleral veins. Anatomically, much more remains to be investigated to better understand how structural changes along this pathway contribute to the regulation of segmental outflow, how anatomical structures distal to Schlemm’s canal, including the collector channels and their ostia and scleral venous plexus, contribute to the regulation of distal outflow resistance. Further development of in vivo assessment of the segmental outflow pattern with optical coherence tomography and aqueous angiography could provide better, individualized treatment plans and outcomes for MIGS surgery.
New Concepts in Glaucoma Surgery Vol.1, pp. 1-38 #1
Edited by: John R. Samples and Iqbal Ike K. Ahmed
© Kugler Publications, Amsterdam, The Netherlands
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