How does primary open-angle glaucoma differ from angle-closure glaucoma?

Primary open-angle glaucoma (POAG) and angle-closure glaucoma differ primarily in the mechanism of fluid blockage and the resulting clinical presentation.

Primary Open-Angle Glaucoma (POAG)

POAG is a chronic condition often linked to degenerative changes in the eye's drainage channels, which impede the outflow of aqueous humor. Because the drainage angle remains open, the blockage is continuous but typically asymptomatic in early stages. Vision loss is slow and progressive, beginning in the peripheral field, and is usually managed with medication to lower intraocular pressure.12

Angle-Closure Glaucoma

This type occurs when the angle between the iris and the wall of the eyeball becomes obstructed, preventing fluid from reaching the drainage system. In cases such as pupillary block, the iris is pushed forward, sealing the angle. Unlike POAG, this often results in acute attacks characterized by:21
* Severe eye pain, headaches, and nausea or vomiting.21
* Blurred vision or halos around lights.2
* A red, hard eye due to rapidly rising pressure.1

While POAG is managed primarily through medication, acute angle-closure glaucoma often requires urgent surgical intervention to create an opening in the iris to restore fluid flow.21