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TYPES OF GLAUCOMA
Most people with glaucoma are divided into those with a pressure above, or within, the normal range. They are further divided into those who have a visibly open drainage network, and those with a closed drainage network.
The drainage network is called the "angle", hence the terms open angle glaucoma and closed angle glaucoma. It needs to be understood, however, that the increase in pressure within the eye is not related to an increase in flow into the eye, but rather a decrease of flow out of the eye. That means that even the "open angle" really represents a blocked drainage network, except that the blockage is at a microscopic level and the eye pressures are often not as high as with the closed angle glaucoma.
Recently, there has been a trend to subdivide those glaucomas that are termed open angle glaucomas by the appearance of the optic disc, as there is some evidence that different processes lead to different patterns of damage. This might ultimately have treatment implications.
Further, there are numerous eye diseases and processes which can increase the likelihood of glaucoma developing, hence causing secondary glaucoma. These include eye inflammation/uveitis, growth of abnormal blood vessels in the eye after an eye stroke or serious diabetic damage, and genetically determined conditions causing the release of pigment in the eye which can block the drainage area. Examples of the latter are pigment dispersion and pseudoexfoliation syndrome.
Lastly, one should not forget the effect of medications. Antihistamines, antidepressant drugs and dilating eye drops can precipitate acute glaucoma in susceptible patients. Even worse are any drugs containing steroids (including creams and sprays), for in susceptible patients they can result in very serious glaucoma. TOP
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