Gourt > Health > Conditions and Diseases > Eye Disorders > Glaucoma (2)
Glaucoma is a group of diseases of the optic nerve involving loss of retinal ganglion cells in a characteristic pattern of optic neuropathy. Although raised intraocular pressure is a significant risk factor for developing glaucoma, there is no set threshold for intraocular pressure that causes glaucoma. One person may develop nerve damage at a relatively low pressure, while another person may have high eye pressures for years and yet never develop damage. Untreated glaucoma leads to permanent damage of the optic nerve and resultant visual field loss, which can progress to blindness.
Types
The most common type, primary open angle glaucoma (POAG) (), frequently has no symptoms and has been nicknamed "the sneak thief of sight". One factor may be a relative obstruction on the outflow of aqueous humour from the eye. Aqueous humour is produced by the epithelium lining the eye's ciliary body which then flows through the pupil and into the anterior chamber. The trabecular meshwork then drains the humour to Schlemm's canal, and ultimately to the venous system. All eyes have some intraocular pressure, which is caused by some resistance to the flow of aqueous through the trabeculum and Schlemm's canal. If the intraocular pressure (IOP) is too high, (>21.5 mm Hg), the pressure exerted on the walls of the eye results in compression of the ocular structures. However, other factors such as disturbances of blood flow in the optic nerve head may interact with IOP to affect the optic nerve. In one third of cases of POAG there is statistically normal IOP. This is called normal tension glaucoma (NTG). Because optic nerve examination and perimetry testing are not always done in addition to IOP measurement in those at risk, NTG is underdiagnosed and the condition presents late. Pigmentary glaucoma, caused by pigment dispersion syndrome, is a form of POAG.
Another type, acute angle-closure glaucoma (AACG) (), is characterized by an acute rise in the intraocular pressure. This occurs in susceptible eyes when the pupil dilates and blocks the flow of fluid through it, leading to the peripheral iris blocking the trabecular meshwork. Acute angle-closure glaucoma can cause pain and reduced visual acuity (blurred vision), and may lead to irreversible visual loss within a short time. This is an ocular emergency requiring immediate treatment. Many people with glaucoma experience halos around bright lights as well as the loss of sight characterized by the disease.
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Do You Suffer From Glaucoma? - Explains this disease; its symptoms, causes, and treatment. Includes why it is important to have a complete eye exam every year.
Meta Description: [ Glaucoma, a disease that damages the optic nerve, affects over three million Americans. Examine the symptoms and signs of glaucoma and learn more about what causes the disease, how it is detected, and the treatments for glaucoma, which may include medications, eye drops, and surgery. ]
eMedicine Health - Glaucoma - Articles about the symptoms, diagnosis, and treatment of the various types of glaucoma.
Meta Description: [ Glaucoma ]
eMedicine Health - Ocular Hypertension - Consumer health resource center providing information on the causes, symptoms, and treatment of ocular hypertension.
Meta Description: [ The term ocular hypertension usually refers to any situation in which the pressure inside the eye, called intraocular pressure, is higher than normal. Eye pressure is measured in millimeters of ... ]
Eye Care Source - Informs about the detection, treatment, and prevention of Glaucoma.
Meta Description: [ A consumer guide to glaucoma, glaucoma symptoms and treatments. ]
Glaucoma Public Education Program - Educational material from the National Eye Institute. Fact sheets can be downloaded.
Meta Description: [ National Eye Institute's National Eye Health Education Program (NEHEP) Web site provides information about large-scale public and professional education programs in partnership with national organizations. ]
Glaucoma Research Center at Wills Eye Hospital - Undertaking studies into treatment, patient quality of life, and how best to screen for the disease.
Meta Description: [ Glaucoma Service Foundation to Prevent Blindness provides glaucoma information on diagnosing, testing and treating glaucoma as well as a chat support group. ]
Glaucoma Service and Foundation - Resources and information about medications, support groups and awareness.
Meta Description: [ Glaucoma Service Foundation to Prevent Blindness provides glaucoma information on diagnosing, testing and treating glaucoma as well as a chat support group. ]
h Factsheets from BUPA - Explains the causes, symptoms and treatment of glaucoma. Available for down loading in Adobe acrobat format.
Meta Description: [ BUPA health information factsheet - glaucoma can cause impairment of vision and if not treated full loss of vision can occur ]
Ophthalmology Review Journal - Glaucoma - A non-profit organization devoted to the education and training of international eye care providers. Lists a number of medical articles and case studies about this severe eye disease.
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Meta Description: [ Glaucoma is a group of diseases in which the pressure in the eye is higher than that particular eye can tolerate. Glaucoma occurs later in life ]
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