glaucoma

Glaucoma is a group of eye diseases that can lead to damage of the optic nerve, which transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of sight" because the loss of vision usually occurs slowly over a long period of time. A major risk factor for glaucoma is increased pressure within the eye, known as intraocular pressure (IOP). It is associated with old age, a family history of glaucoma, and certain medical conditions or the use of some medications. The word glaucoma comes from the Ancient Greek word (), meaning 'gleaming, blue-green, gray'.

Of the different types of glaucoma, the most common are called open-angle glaucoma and closed-angle glaucoma. Inside the eye, a liquid called aqueous humor, which is produced by the ciliary body, helps to maintain shape and provides nutrients. The aqueous humor normally drains through the trabecular meshwork. In open-angle glaucoma, the drainage is impeded, causing the build up of aqueous to accumulate in the anterior chamber causing the pressure inside the eye to increase. This elevated pressure can reduce vascular perfusion in the vitreous chamber and can damage the optic nerve and peripheral glial tissues. In closed-angle glaucoma, the drainage of the eye becomes suddenly blocked, leading to a rapid increase in intraocular pressure. This may lead to intense eye pain, blurred vision, and nausea. Closed-angle glaucoma is an emergency requiring immediate attention.