Aqueous humor

the aqueous humor is a clear, watery fluid that fills the anterior and posterior chambers of the eye. It is produced continuously by the ciliary processes of the ciliary body and plays an essential role in maintaining intraocular pressure, nourishing avascular ocular tissues, and preserving optical transparency.

Production, flow, and drainage

After being secreted into the posterior chamber (the space between the iris and lens), aqueous humor flows through the pupil into the anterior chamber, the space between the cornea and iris. It then drains mainly through the trabecular meshwork into the canal of Schlemm at the iridocorneal angle, eventually entering the venous circulation.

Functions

Aqueous humor is composed primarily of water, electrolytes, amino acids, glucose, vitamin C, and dissolved gases. Compared with plasma, it contains very low protein content, which helps maintain optical clarity.

Its major functions include:

• Maintaining intraocular pressure and the shape of the eyeball

• Providing nutrients and oxygen to the cornea and lens, which are avascular

• Removing metabolic waste products

• Maintaining a transparent optical medium for light transmission

Clinical correlate

Clinically, impaired drainage of aqueous humor leads to increased intraocular pressure and may cause glaucoma, damaging the optic nerve and impairing vision if untreated.