The anterior chamber (AC) is the aqueous humor-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium.
In hyphema, blood fills the anterior chamber as a result of a hemorrhage, most commonly after a blunt eye injury.
In glaucoma, blockage of the trabecular meshwork prevents the normal outflow of aqueous humour, resulting in increased intraocular pressure, progressive damage to the optic nerve head, and eventually blindness.
Determining the anterior chamber depth (ACD) is important in estimating the risk of angle closure glaucoma.
A simpler clinical method of quantitatively estimating ACD using smartphone photography (EZ ratio) was developed by Dr Ehud Zamir from the Centre for Eye Research Australia, the University of Melbourne, and published in 2016.
Figure 1. Calculating EZ ratio.
Figure 2. Different anterior chamber depths as seen from the lateral perpendicular (profile) view. The more forward the pupil is, the shallower the anterior chamber. In the leftmost photo, the pupil is relatively posterior (set back), indicating an EZ ratio of < 0.5 and an anterior chamber deeper than 2.5 mm. In the middle photo, the pupil is midway between the sclera posteriorly and the cornea anteriorly, indicating an EZ ratio of 0.5, and a medium chamber depth of about 2.5 mm. In the rightmost photo, the pupil is very anterior (forward), indicating an EZ ratio of more than 0.5 and a shallow anterior chamber of less than 2.5 mm.
