• Open-angle glaucoma: This is characterized by elevated IOP with an anatomically open anterior chamber. Sclerosed trabecular tissue impairs aqueous filtration and drainage. As treatment, miosis and trabecular stretching should be produced medically (eyedrops, epinephrine, timolol).

• Closed-angle glaucoma: The peripheral iris moves in direct contact with the posterior corneal surface, mechanically obstructing aqueous flow. This is caused by a narrow angle between the iris and posterior cornea and produces swelling of the crystalline lens.

• Congenital glaucoma is associated with some eye diseases (retinopathy of prematurity, aniridia, mesodermal dysgenesis syndrome). Surgical goniotomy or trabeculotomy should be performed to route aqueous flow into Schlemm canal. Cyclocryotherapy decreases aqueous formation by destroying the ciliary body by freezing tissue with a probe.