The aqueous humour, or aqueous, is the clear, watery fluid in the eye that fills the space between the back surface of the cornea and the front surface of the vitreous humour.Cassin, B. and Solomon, S. Dictionary of Eye Terminology. Gainsville, Florida: Triad Publishing Company, 1990.

The anterior segment is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens."Departments. Anterior segment." Cantabrian Institute of Ophthalmology. Within the anterior segment are two fluid-filled spaces divided by the iris plane: 1) the anterior chamber between the posterior surface of the cornea (i.e. the corneal endothelium) and the iris, and 2) the posterior chamber between the iris and the front face of the vitreous. Aqueous humor fills these spaces within the anterior segment to provide nutrients to the lens and corneal endothelium, and its pressure maintains the convex shape of the cornea.Miguel Coca-Prados, Ph.D.Uzzle T. "The Eye, the Ear, and the Brain."

In health the aqueous humour does not mix with the firm, gel-like vitreous humour because of the lens and its suspensory ligaments between the two. The aqueous humour is secreted into the posterior chamber by the ciliary body, specifically the ciliary processes, and flows through the narrow cleft between the front of the lens and the back of the iris, to escape through the pupil into the anterior chamber, and then to drain out of the eye via the trabecular meshwork into the aqueous veins and eventually into the veins of the orbit.

Glaucoma is a condition characterised by increased intraocular pressure (pressure within the eye) either through increased production or decreased outflow of aqueous humor.^* Increased resistance to outflow of aqueous humour may occur due to an abnormal trabecular meshwork, or to obliteration of the meshwork due to injury or disease of the iris. Uncontrolled glaucoma typically leads to visual field loss and ultimately blindness.

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Body fluids | Eye

Kammerwasser | Humor acuoso | Humeur aqueuse | humor aquoso | 房水