What is an aqueous humor and what does the aqueous humor do? The aqueous humor is a transparent, watery fluid similar to plasma, however consisting of low protein concentrations. It is produced from the ciliary epithelium, a structure supporting the lens. It fills both the anterior and the posterior chambers of the eye, and is not to be confused with the vitreous humor, which is located in the space between the lens and the retina, also called the posterior cavity or vitreous chamber.
Aqueous Humor Structure
- Amino acids: transferred by ciliary muscles
- 98% water
- ElectrolytesmM
- Sodium = 142,09 Potassium = 2,2 – 4,0 Calcium = 1,8 Magnesium = 1,1 Chlorite = 131,6 HCO ³- = 20,15 Phosphate = 0,62 pH = 7,4 Osm = 304
- Ascorbic acid
- Glutathione
- Immunoglobulins
Functions of an Aqueous Humor
- Keeps the intraocular pressure and pumps up the globe of the eye. It is this hydrostatic pressure which keeps the eyeball in a roughly round shape and keeps the walls of the eyeball tight.
- Offers 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 sector to act as an antioxidant agent.
- Presence of immunoglobulins suggest a role in immune action to defend against pathogens.
- Supplies inflation for expansion of the cornea and thus increased security against dust, wind, pollen grains and some pathogens.
for refractive index.
Production Function of Aqueous Humor
The primary eye structures connected to aqueous humor dynamics are the ciliary body (the site of aqueous humor production), and the trabecular meshwork and the uveoscleral path (the principal places of aqueous humor outflow).
Aqueous humor is produced into the posterior chamber by the ciliary body, particularly the non-pigmented epithelium of the ciliary body (pars plicata). 5 alpha-dihydrocortisol, an enzyme hindered by 5-alpha reductase inhibitors, might be associated with production of aqueous humor.
What Does Aqueous Humor Do for Drainage in Eye
Aqueous humor is constantly produced by the ciliary processes and this rate of production need to be balanced by an equal rate of aqueous humor drainage. Small variations in the production or outflow of aqueous humor will have a large influence on the intraocular pressure.
The drain route for aqueous humor circulation is first through the posterior chamber, then the narrow space in between the posterior iris and the anterior lens (contributes to small resistance), through the student to go into the anterior chamber. From there, the aqueous humor exits the eye through the trabecular meshwork into Schlemm’s canal (a channel at the limbus, i.e., the signing up with point of the cornea and sclera, which encircles the cornea) It streams through 25-30 collector canals into the episcleral veins. The best resistance to aqueous flow is offered by the trabecular meshwork (esp. the juxtacanalicular part), and this is where most of the aqueous outflow happens. The internal wall of the canal is very delicate and allows the fluid to filter due to high pressure of the fluid within the eye. The secondary route is the uveoscleral drain, and is independent of the intraocular pressure, the aqueous circulations through here, but to a lower level than through the trabecular meshwork (approx. 10% of the total drainage whereas by trabecular meshwork 90% of the total drain).
The fluid is normally 15 mmHg (0.6 inHg) above air pressure, so when a syringe is injected the fluid flows quickly. If the fluid is leaking, due to collapse and wilting of cornea, the solidity of the normal eye is for that reason supported.
Medical significance
Glaucoma is a progressive optic neuropathy where retinal ganglion cells and their axons pass away triggering a corresponding visual field problem. An important risk aspect is increased intraocular pressure (pressure within the eye) either through increased production or reduced outflow of aqueous humor. Increased resistance to outflow of aqueous humor might occur due to an unusual trabecular mesh work or to obliteration of the meshwork due to injury or disease of the iris. However, increased interocular pressure is neither enough nor necessary for advancement of main open angle glaucoma, although it is a major risk element. Unrestrained glaucoma normally causes visual field loss and ultimately blindness.
