Aqueous humor

Aqueous Humor

The aqueous humor is a transparent, watery fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary body, a part of the eye that lies behind the iris. The aqueous humor fills both the anterior chamber and the posterior chamber of the eye, and provides nutrition to the lens and the cornea, which do not have their own blood supply.

Composition

The aqueous humor is composed primarily of water, but also contains electrolytes, glucose, amino acids, ascorbic acid, glutathione, and a small quantity of protein. The composition of the aqueous humor is carefully controlled by the ciliary epithelium, which has ion transport systems that regulate the flow of substances into and out of the fluid.

Function

The primary functions of the aqueous humor are to provide nutrition to the avascular ocular tissues (cornea and lens), and to maintain the intraocular pressure of the eye. The aqueous humor also serves to transport ascorbic acid, an antioxidant that protects the eye from oxidative damage, and other substances that are secreted into the fluid by the ciliary body.

Pathology

Abnormalities in the production, circulation, or drainage of the aqueous humor can lead to a number of eye disorders. For example, glaucoma is a condition that is often caused by an increase in the intraocular pressure of the eye, which can occur if the aqueous humor is not drained properly.

See also

• Vitreous humor
• Intraocular pressure
• Glaucoma
• Ciliary body
• Anterior chamber of the eye
• Posterior chamber of the eye