Posterior chamber
Camera posterior bulbi
The small, ring-shaped aqueous-filled space behind the iris and in front of the lens and zonule, into which the ciliary processes secrete aqueous humour.
Overview
The posterior chamber is bounded anteriorly by the iris, posteriorly by the lens and zonular fibres (and the anterior vitreous face peripherally), and laterally by the ciliary processes. It holds only ≈0.06 mL of aqueous. Aqueous secreted here flows forwards between the iris and lens through the pupil into the anterior chamber.
If the iris becomes stuck to the lens (posterior synechiae from uveitis) or apposes it tightly (relative pupil block in a hyperopic eye), aqueous accumulates in the posterior chamber and pushes the peripheral iris forwards (iris bombé), closing the angle. A laser peripheral iridotomy provides an alternative route to the anterior chamber.
"Posterior chamber" (behind the iris) must not be confused with the vitreous chamber (behind the lens); posterior-chamber intraocular lenses are placed in the capsular bag or ciliary sulcus.
- Location
Behind the iris, in front of the lens and zonule, bounded laterally by the ciliary processes.
Function
- Receive freshly secreted aqueous humour from the ciliary processes
- Conduct aqueous to the anterior chamber via the pupil
Clinical significance
Pupil block and iris bombé
Obstruction of aqueous flow through the pupil raises posterior-chamber pressure and bows the iris forward to close the drainage angle — the mechanism of primary angle-closure glaucoma, relieved by peripheral iridotomy.
Compiled from standard anatomy and physiology references — see the Special Senses sources. For education only; not medical advice.