The aqueous compartment is made up of two chambers; anterior and posterior.
The aqueous humour is continually produced by the ciliary body, primarily by active secretion and to a lesser degree by passive diffusion / ultrafiltration. After production, the aqueous moves to the posterior chamber, through the pupil and into the anterior chamber.
The production of aqueous, and its volume within the aqueous chambers, contributes to the intra-ocular pressure (IOP), therefore there must be continuous drainage to balance the production otherwise the IOP will rise, which can lead to glaucoma. The reference range for IOP in cats and dogs is 15 – 25 mmHg.
The majority of the aqueous drains at the drainage angle (located at the junction of the base of the iris and the corneoscleral tissue).
