Aqueous humor
Aqueous humor
The aqueous humour is a transparent watery fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary epithelium, a structure supporting the lens.[1] It fills both the anterior and the posterior chambers of the eye, and is not to be confused with the vitreous humour, which is located in the space between the lens and the retina, also known as the posterior cavity or vitreous chamber.
Maintains the intraocular pressure and inflates the globe of the eye. It is this hydrostatic pressure which keeps the eyeball in a roughly spherical shape and keeps the walls of the eyeball taut.
Provides nutrition (e.g. amino acids and glucose) for the avascular ocular tissues; posterior cornea, trabecular meshwork, lens, and anterior vitreous.
May serve to transport ascorbate in the anterior segment to act as an antioxidant agent.
Presence of immunoglobulins indicate a role in immune response to defend against pathogens.
Provides inflation for expansion of the cornea and thus increased protection against dust, wind, pollen grains and some pathogens.
for refractive index.
Aqueous humour is secreted into the posterior chamber by the ciliary body, specifically the non-pigmented epithelium of the ciliary body (pars plicata). 5 alpha-dihydrocortisol, an enzyme inhibited by 5-alpha reductase inhibitors, may be involved in production of aqueous humour.
Glaucoma is a progressive optic neuropathy where retinal ganglion cells and their axons die causing a corresponding visual field defect. An important risk factor is increased intraocular pressure (pressure within the eye) either through increased production or decreased outflow of aqueous humour.[6] Increased resistance to outflow of aqueous humour may occur due to an abnormal trabecular meshwork or due to obliteration of the meshwork resulting from injury or disease of the iris. However, increased interocular pressure is neither sufficient nor necessary for development of primary open angle glaucoma, although it is a major risk factor. Uncontrolled glaucoma typically leads to visual field loss and ultimately blindness.
Uveoscleral outflow of aqueous humour can be increased with prostaglandin agonists, while trabecular outflow is increased by M3 agonists. Fluid production can be decreased by beta blockers, alpha2-agonists, and carbonic anhydrase inhibitors.
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