I've been around cats all my life. I know their diseases run parallel with ours: diabetes, upper respiratory, cancer, cataracts, etc. but I didn't realize they could get glaucoma. When I took Faux in to get her eyes checked, I was expecting something more along the lines of cataracts or possibly a tumor, but she was diagnosed with glaucoma. She's now on eye drops to bring down the pressure. If left untreated the eye could rupture.
The disease is a result of fluid pressure building in the eyeball. To diagnose glaucoma, like humans, the pressure must be measured. Topical and or oral drugs are used to reduce the pressure. If the drugs don't work, surgery is sometimes required. The surgery can be to remove the pressure or the eye.