What is the difference between narrow-angle glaucoma and other types of glaucoma?

Narrow drain: Narrow angle glaucoma refers to when the drain or trabecular meshwork of the eye is blocked visually when viewed. In other words, there is scarring across the drain of the eye, or possibly a shallow anterior chamber (small eye) with a large lens makes the drain approach narrow with the iris up again the meshwork. This is differentiated from open angle though mixed states exist.

Glaucoma types: Most glaucoma is open angle - the fluid drainage space in the front is wide and the drains within it are obstructed leading to increased pressure over time. Narrow angle, mostly in hyperopes (those with eyeglass lenses that act as magnifiers), can in older folks (over 50 or so), quickly within hours mechancially block fluid flow causing an acute glaucoma attack. This is an emergency!