The shape of the front part of the eye is maintained by a fluid called aqueous humour.
Aqueous humour is made by the ciliary body. Strands from the ciliary body support the lens behind the coloured part of the eye (iris).
Aqueous humour flows into the front of the eye through the pupil.
Aqueous humour drains out of the eye through the trabecular meshwork. The trabecular meshwork is a spongy mass of tiny canals located in the drainage angle. The drainage angle is located between the iris and the clear covering of the eye (cornea), where the iris meets the white outer covering (sclera) of the eye.
Aqueous humour is returned into the bloodstream through a tiny channel (Schlemm's canal) located under the trabecular meshwork.
Aqueous humour is produced by and removed from the eye at a constant rate [about 1 tsp (5 mL) a day] to maintain a constant pressure in the front (anterior) chamber of the eye. While pressure in the eye varies throughout the day, the normal pressure within the eye is 10 mm Hg to 21 mm Hg.
Medical Review:Adam Husney MD - Family Medicine & Anne C. Poinier MD - Internal Medicine & Christopher J. Rudnisky MD, MPH, FRCSC - Ophthalmology