Dictionary > Aqueous humor

Aqueous humor

noun, plural: aqueous humors
A clear, watery body fluid secreted by the ciliary epithelium, and fills the anterior and the posterior chambers of the eye
The aqueous humor is one of the body fluids found within the eyeball. It is clear and watery similar to plasma. Nevertheless, it has fewer proteins than plasma. Its main component is water (98%). Other components include amino acids, electrolytes (e.g. sodium, potassium, calcium, magnesium, chloride, bicarbonate, phosphate, etc.), ascorbic acid, glutathione, and immunoglobulins.
The aqueous humor is produced and secreted by the ciliary epithelium, particularly the non-pigmented part (pars plicata). The fluid, then, passes through the pupil, and fills the anterior and the posterior chambers of the eye.
Some of the functions of the aqueous humor are for maintaining the intraocular pressure (which is essential in keeping the roughly spherical shape of the eyeball), for providing nutrition to the avascular ocular tissues, for immune activity (through the presence of immunoglobulin).
Maintaining proper intraocular pressure is important because an increased intraocular pressure means an increased risk to glaucoma, a progressive optic neuropathy resulting in visual defect or loss.
The aqueous humor is different from the vitreous humor, which fills the vitreous chamber or the eye.

  • aqueous humour

See also:

  • vitreous humour
  • glaucoma

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