Ocular Hypotensive Medications for the Treatment of Glaucoma

Glaucoma is presently one of the most common causes of irreversible blindness in the world. Glaucoma is a group of eye diseases characterized by a progressive optic neuropathy that causes vision loss usually initially affecting the peripheral visual field and, when untreated, eventually affecting the central vision, causing total blindness [1]. Risk factors for the development of glaucoma include elevated intraocular pressure (normal range: 10–21 mm Hg), increasing age (although it can occur congenitally), a family history of glaucoma (several genes have been associated with it), thin corneas, enlarged optic nerve head cup-to-disc ratio, black ethnicity for open angle glaucoma [2], Asian ethnicity for angle closure glaucoma, ocular trauma, and possibly other systemic diseases like hypertension and diabetes mellitus [3]. The cause for the elevated intraocular pressure when it occurs in glaucomatous eyes is from reduced aqueous humor outflow from the eye. The treatment for glaucoma is directed to lowering the intraocular pressure to a level that is low enough to prevent progressive glaucomatous optic neuropathy and further visual field loss. Blindness from glaucoma can be avoided by early diagnosis and successful treatment; however, unfortunately, repair of glaucomatous optic neuropathy and restoration of lost vision are not possible presently (see the article elsewhere in this issue by Levin on neuroprotection and regeneration in glaucoma). Various treatment options are available to the patient with glaucoma to prevent blindness depending on the type and cause of the elevated intraocular