Glaucoma

Glaucoma is the second leading cause of permanent blindness in the United States and occurs most often in older adults. There are four general categories of adult glaucoma: primary open-angle and angle-closure, and the secondary open and angle-closure glaucoma. The most common type in the United States is primary, open-angle glaucoma (POAG). Glaucoma is defined as an acquired loss of retinal ganglion cells and axons within the optic nerve or optic neuropathy that results in a characteristic optic nerve head appearance and a corresponding progressive loss of vision. This pattern of peripheral loss of vision can also be a distinguishing characteristic from other forms of vision loss. The patient with POAG is often asymptomatic until the optic nerve damage is severe unless signs of early glaucoma are recognized on a routine eye exam. Acute angle-closure glaucoma, in contrast, can develop suddenly and result in a more rapid decline in vision with associated corneal edema, eye pain, headache, nausea, and emesis. Secondary glaucoma is usually correlated with a prior eye injury or disease state, causing elevated intraocular pressure (IOP) and related optic neuropathy. The last type is normal or low-tension type glaucoma in which patients have the same visual loss pattern as POAG but at normal intraocular pressure readings. While there are congenital, infantile, development glaucomas, and a juvenile variant of POAG, the four previously mentioned glaucoma types typically occur in people over the age of 40. The cause is generally correlated with increased intraocular pressure, though it has not been proven to have a direct cause-and-effect relationship. There may also be a genetic component to the development of glaucoma. Monozygotic twin pairs have a higher percentage of concordance, but not pairs, which suggests that environmental factors also influence the development of the disease. Currently, glaucoma cannot be prevented or cured, but progression can be controlled to help prevent further vision loss either through medication, glaucoma laser treatment, or incisional glaucoma surgeries.