Glaucoma is a group of diseases in which intraocular pressure rises above normal. The retina is at risk of serious permanent damage under these conditions. Closed angle glaucoma results from the pressure pushes the lens against the iris, which prevents aqueous flow through the pupil space. Open angle glaucoma is when the there is no blockage.

Treatment involves use of drugs to reduce aqueous production and/or to allow increased fluid outflow. Pilocarpine, an acetylcholine mimetic, is used to stretch the trabecular tissues to allow the aqueous humor to flow out through the canal of Schlem. Beta₂ antagonists may be used for open angle glaucoma since these agents reduce the production of vitreous fluid.