The aqueous humour is a clear, watery fluid that occupies the anterior chamber, which is the space between the cornea (front part of the eye) and iris (coloured region that regulates the amount of light entering the eye). It is secreted by the ciliary body to nourish the iris/lens/cornea and provide the necessary environment for clear vision. From the ciliary body, the aqueous humour flows through the pupil (opening at the centre of the iris) and fills the anterior chamber. From here, it gets drained through the trabecular meshwork (porous tissue), present at the angle formed by the iris and cornea (drainage angle), into a channel (Schlemm’s canal) that empties the aqueous humour into the blood stream.
The balance between production and drainage of aqueous humour is an essential determinant of intraocular pressure (fluid pressure inside the eye). Reduced flow of aqueous humour out of the eye may cause increased eye pressure which in turn may cause optic nerve damage, retinal vascular occlusion or corneal decompensation.