Abnormally low intraocular pressure, usually less than 6 mmHg. It may result from trauma in which there is a perforating wound with loss of aqueous, concussion injury or following surgery for glaucoma. Persistent hypotony may result in visual impairment due to choroidal folds, choroidal detachment, retinal folds or retinal detachment. Syn. ocular hypotonia; ocular hypotonus. See choroidal folds; cyclodialysis.