The shape of the front part of the eye is maintained by a fluid
called aqueous humor.
Aqueous humor is made by the ciliary body.
Strands from the ciliary body support the lens behind the colored part of the
eye (iris). See an illustration of
the iris and lens.
Aqueous humor flows into the front of the eye
through the pupil.
Aqueous humor 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.
humor is returned into the bloodstream through a tiny channel (Schlemm's canal)
located under the trabecular meshwork.
Aqueous humor is produced by and removed from the eye at a constant
rate [about 1 tsp (5 mL) per
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.