The Mechanobiology of Aqueous Humor Transport across Schlemm’s Canal Endothelium
Intraocular pressure (IOP) is controlled by the turnover of aqueous humor, a clear ”uid that ™lls the anterior segment of the eye and serves to nourish the avascular tissues of the cornea, lens, and trabecular meshwork (Figure 17.1). Aqueous humor is secreted into the posterior chamber by the ciliary processes, enters the anterior chamber through the pupil, and drains through one of two out”ow pathways. The conventional or trabecular out”ow pathway carries the majority of out”ow and includes the trabecular meshwork, Schlemm’s canal, and downstream collecting vessels that lead to the episcleral veins. The secondary uveoscleral out”ow pathway appears to account for only 3%–35% of total out”ow in the human eye (as surveyed by Nilsson ) and likely contributes little toward IOP regulation, although uveoscleral out”ow does become important for glaucoma therapies involving prostaglandins and its analogues.