As in all forms of glaucoma, the end-organ damage is the optic nerve head. A sufficiently elevated IOP will damage the optic nerve, which is the structure that connects what the eyes see to the brain.
The “angle” is the part of the eye where the iris meets the cornea and the sclera. The drainage system of the eye is located at this region – trabecular meshwork. (See Open angle glaucoma.)
In primary angle closure glaucoma, the part of the angle where the trabecular meshwork is located is closed/obstructed by the peripheral iris. This angle closure leads to IOP rise and damage to the optic nerve. Angle closure glaucoma usually affects anatomically “small eyes” – in which intra-ocular structures within a limited space area results in a crowded anterior segment.
It typically affects more women than men, and although it may occur in any individual, it is more common in some ethnic groups (i.e. Chinese). Most of the cases are asymptomatic, but some show quite intense symptoms. (See Acute angle closure.)
The most common mechanism of angle closure is called pupillary block, and it occurs due to relative block of fluid flow at the level of the pupil (from the posterior to anterior part of the eye), which makes the pressure at the posterior chamber to increase, leading to a forward bowing of the iris and narrowing of the angle
Differentiation between an open angle and a closed angle glaucoma is important because the treatment approach differs, as we may use additional procedures to treat angle closure glaucoma when compared to open angle glaucoma cases.