aqueous humour


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Related to aqueous humour: vitreous humour

aqueous humour

The watery fluid filling the front chamber of the eye between the back of the CORNEA and the front of the IRIS.

aqueous humour

fluid that fills the space between the cornea and the lens of the vertebrate EYE (see Fig. 156 ).

humour, aqueous

Clear, colourless fluid that fills the anterior and posterior chambers of the eye. It is a carrier of nutrients for the lens and to a larger extent the cornea, especially of glucose and essential amino acids. It contributes to the maintenance of the intraocular pressure. It is formed in the ciliary processes, flows into the posterior chamber, then through the pupil into the anterior chamber and leaves the eye through the trabecular meshwork passing to the canal of Schlemm and then to veins in the intrascleral venous plexus (Fig. H3). A small amount (10% to 15%) also flows out of the eye via the uveoscleral pathway. The aqueous in the anterior chamber is a component of the optical system of the eye. It has an index of refraction of 1.336, slightly lower than that of the cornea, so that the cornea/aqueous surface acts as a diverging lens of low power. It is a fluid very similar to blood plasma but with a much lower concentration of protein and a higher concentration of ascorbate.The rate of aqueous humour outflow varies between 2.0 μl/min and 3.0 μl/min via both the conventional (trabecular meshwork and Schlemm's canal) and the unconventional (uveoscleral) pathways. This rate is normally equal to the rate of aqueous secretion. If the rate of outflow is lower than the rate of secretion intraocular pressure increases. See aqueous flare; ultrafiltration.
Fig. H3 Outflow of aqueous humourenlarge picture
Fig. H3 Outflow of aqueous humour
References in periodicals archive ?
Contraction of the ciliary muscle produces traction on the trabecular meshwork, facilitating aqueous humour drainage and lowering IOP [6].
In the research published in the journal Experimental Eye Research, the team measured the changes in the artificial aqueous humour, and found, one hour later, higher levels of glutathione and adenosine triphosphate, which is thought to activate a system to alter the outflow of aqueous humour in the eye.
1 Acute angle closure glaucoma (AACG) is a possible blinding situation represented by an unexpected and pronounced rise in intraocular pressure (IOP) due to obstruction of aqueous humour outflow.
Diagnosis on basis of clinical signs and activity of worm in aqueous humour and was confirmed by surgical removal of the parasite.
On the other hand, decreased glucose concentration in the aqueous humour could also cause a transient difference in osmotic pressure between the aqueous humour and crystalline lens.
They reduce IOP by either slowing the rate of aqueous humour formation or increasing aqueous outflow.
We know this is how the aqueous humour leaves the eye so the finding sheds light on the biological processes involved and may lead to new drug targets"
This article continues from the previous article in this series, by outlining the complications that occur in the aqueous humour, iris, pupil, lens and refractive state of people with DM.
The role of the aqueous humour in the anterior chamber is threefold: it provides nutrients to the crystalline lens and corneal endothelium, removes metabolic waste by-products and maintains an intraocular pressure (IOP) to keep the eye inflated.
The following two chapters introduce the reader to aqueous humour dynamics and how the pathophysiology of glaucomatous damage occurs in terms of the mechanical and vascular theories of damage.
The riboflavin in the cornea is activated by this exposure whilst the riboflavin that has entered the aqueous humour protects the internal structures (such as the lens and retina) from the effects of UV light.
The aqueous humour transmits most infrared except in a few selected regions where it absorbs.