pathophysiology of glaucoma

Topics: Glaucoma, Intraocular pressure, Eye Pages: 8 (1454 words) Published: June 5, 2014


Pathophysiology of Glaucoma – Glaucoma is “a disease of the eye in which fluid pressure within the eye rises - if left untreated the patient may lose vision, and even become blind. The disease generally affects both eyes,” Medical News Today (2012). The anterior chamber is a small space located in front of the eye. Clear fluid (aqueous humor) flows in and out of this chamber, as the fluid flows it nourishes and bathes nearby tissues. Persons who suffer from glaucoma have problem with this fluid. It does not drain properly out of the eye. At times it may drain too slowly and this causes the fluid to accumulate in the eye. When the fluid builds up it causes the eye pressure to rise. The pathophysiology of glaucoma occurs when there is an increase in pressure in the intraocular area. A permanent raise in intraocular pressure of 21 mmHg and over would trigger the onset of glaucoma. When this pressure rises, it presses on and causes harm to the optic nerve. Any damage to the optic nerve would prevent visual information from being sent to the brain and therefore visual loss occurs. The exact pathophysiology of glaucoma is not fully comprehended but experts believe that the rise in pressure on the retina causes cells and nerve ganglions in the retina to die. Moreover, compression of small blood vessels occur in the retina and this deprives it from its nutrients. This contributes to loss of peripheral visual field and eventually the person may become blind.

Etiology of Glaucoma - A gland behind the upper eyelid fills the anterior chamber with a clear fluid. This clear fluid is called the aqueous humor and it supplies the eye with oxygen and nutrients. This assists with inflation of the eyes. A steady production of the liquid drains through a mesh of tiny holes behind the lower eyelid. In glaucoma, the liquid is produced normally but the trabecular meshwork cannot drain it due to clogging or some other reason. Liquid pressure builds up in the eye, pressing on the optic nerve (the nerve that links the eye to the brain). There is death of the nerve cell as they are slowly strangled of blood and this causes it to eventually die. The outer nerves fail first, so vision loss tends to start at the edges, progressing to "tunnel vision" and blindness. Many people do not notice this at first, and there is usually no pain, so glaucoma can be quite advanced before it's detected.

The two main types of glaucoma are open angle and closed angle (angle closure) glaucoma. Other types of glaucoma include; pigmentary glaucoma, congenital glaucoma and normal tension glaucoma (NTG). The etiology of glaucoma would be based on the type of glaucoma. There is no known cause for open angle glaucoma. In this type, eye pressure slowly occurs over time and it pushes on the optic nerve. Persons who are of African descent and persons who have family members that suffer from glaucoma stand a greater risk of getting the disease. In angle closure glaucoma, the fluid in the eyes is blocked and it causes severe, painful rise in eye pressure. Eye drops and certain medications may cause an onset of angle closure glaucoma.

Congenital glaucoma affects children between the age of birth and three years. Some patients may get the disease through inheriting it from their parents. Others may get it if their network of cells and tissues were not fully developed before birth. The improper development of the network of cells and tissues in the eyes would lead to improper draining of the aqueous humor. Eventually this would lead to a build-up of fluid in the eyes which would lead to an increase in eye pressure which would then lead to glaucoma. Theorists believe that normal tension glaucoma is caused by fragile optic nerve that can be damage even if the pressure is normal inside the eye. Another possible cause for normal tension glaucoma is reduced blood flow to the optic nerve because of ischemia or vasospasm. Signs and Symptoms of Glaucoma - There is...
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