|physiol the watery fluid within the eyeball between the cornea and the lens|
optically clear, slightly alkaline liquid that occupies the anterior and posterior chambers of the eye (the space in front of the iris and lens and the ringlike space encircling the lens). The aqueous humour resembles blood plasma in composition but contains less protein and glucose and more lactic acid and ascorbic acid. It provides these nutrients (as well as oxygen) to eye tissues that lack a direct blood supply (such as the lens) and also removes their waste products. In addition, it provides an internal pressure, known as intraocular pressure, that keeps the eyeball (globe) properly formed. Aqueous humour is formed from the blood by filtration, secretion, and diffusion through the ciliary body, a muscular structure located behind the iris that controls the curvature of the lens. Aqueous humour leaves the eye through the porous trabecular meshwork and flows into Schlemm's canal, a ringlike passageway around the outer angle of the anterior chamber in front of the iris. From the canal the liquid enters the veins
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