The two major categories of glaucoma are open-angle glaucoma (OAG) and narrow angle glaucoma. The "angle" in both cases refers to the drainage angle inside the eye that controls the outflow of the watery fluid (aqueous) that is continually being produced inside the eye.

If the aqueous can access the drainage angle, the glaucoma is known as open angle glaucoma. If the drainage angle is blocked and the aqueous cannot reach it, the glaucoma is known as narrow angle glaucoma.

Variations of OAG include:

Primary Open Angle Glaucoma (POAG)

Normal-Tension Glaucoma (NTG)

Pigmentary Glaucoma

Pseudoexfoliation Glaucoma

Secondary Glaucoma 

Congenital Glaucoma

Variations of narrow angle glaucoma include:

Acute Angle Closure Glaucoma,

Chronic Angle Closure Glaucoma

Neovascular Glaucoma