The aqueous humour is a transparent water-like fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. 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.  Blood cannot normally enter the eyeball. Aqueous humour, optically clear, slightly alkaline liquid that occupies the anterior and posterior chambers of the eye (the space in front of the iris and lens and the ring like space encircling the lens).The aqueous humour resembles blood plasma in composition but contains less protein and glucose and more lactic acid and ascorbic acid.

Aqueous humour is continually produced by the ciliary processes and this rate of production must be balanced by an equal rate of aqueous humour drainage. Small variations in the production or outflow of aqueous humour will have a large influence on the intraocular pressure.

The drainage route for aqueous humour flow is first through the posterior chamber, then the narrow space between the posterior iris and the anterior lens (contributes to small resistance), through the pupil to enter the anterior chamber. From there, the aqueous humour exits the eye through the trabecular meshwork into Schlemm's canal (a channel at the limbus, i.e., the joining point of the cornea and sclera, which encircles the cornea) It flows through 25–30 collector canals into the episcleral veins. The greatest resistance to aqueous flow is provided by the trabecular meshwork (esp. the juxtacanalicular part), and this is where most of the aqueous outflow occurs. 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 drainage, and is independent of the intraocular pressure, the aqueous flows through here, but to a lesser extent than through the trabecular meshwork (approx. 10% of the total drainage whereas by trabecular meshwork 90% of the total drainage).

The fluid is normally 15 mmHg (0.6 inHg) above atmospheric pressure, so when a syringe is injected the fluid flows easily. If the fluid is leaking, the hardness of the normal eye is compromised, leading to collapse and wilting of the cornea. 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.

Optometry: Open Access Journal deals with eyes and related structures which includes such as vision, processing information related to vision. Optometrists are health professionals provide care related to vision. They give a clear idea related to diagnosis, treatment and management of vision. Optometry journal deals with medications, vision tests and abnormalities of eye.

Manuscripts can be submitted online at https://www.scholarscentral.org/submissions/optometry-open-access.html or send an email attachment to optometry@emedsci.com

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Hannah
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Optometry: Open Access
ISSN: 2476-2075
omoa@emedicalsci.org