High intraocular pressure and glaucoma
Glaucoma patients have an imbalance between the production and drainage of internal fluids in the eye. These internal fluids are essential for maintaining a normal level of intraocular pressure (IOP), so that the eye can stay with globe-like shape. Certain internal structures are responsible for maintaining the normal flow of eye fluids. People with glaucoma always have high IOP because internal fluids do not drain normally and begin to build up inside the eye. High IOP will push and damage optic nerve and then vision loss can be caused.
Why glaucoma is often associated with a high IOP
There is an underlying reason that why glaucoma always brings high IOP. It involves the internal structure of the eye and the way in which internal fluids flow. The ciliary body in the eye generates eye fluid, whose formal name is aqueous humor. Since the ciliary body is behind the iris, eye fluids first flow behind the iris and through the pupil, and then fill the anterior chamber. Later, eye fluids pass through the filtration angle, flow through the sclera and then join with the outside network. In this process, the filtration angle is critical for maintaining normal IOP. Once eye fluids can not pass through it, IOP begins to rise. By narrowing the filtration angle or damaging the angle’s internal tissues, glaucoma hinders the outflow of eye fluids.
Some unusual cases of glaucoma
It is worth mentioning that not all cases of glaucoma are accompanied with a high IOP. A special type of glaucoma named normal-tension glaucoma just has normal IOP. But these patients have highly pressure-sensitive optic nerves. Decreased blood flow is suspected to cause this type of glaucoma. Exceptions also happen to people with elevated pressure named ocular hypertension. They never develop glaucoma.
How to diagnose different types of glaucoma
Since not all types of glaucoma cause a high IOP, traditional screenings can not detect certain types of glaucoma such as normal-tension glaucoma. These screening methods just test the presence of high IOP. Detection of a high IOP is traditionally the standard way to diagnose regular glaucoma cases. But the exceptional cases mentioned above require other methods. The most ensuring way is to examine the optic nerve directly, e.g. using a visual field testing.
Other contributing factors to glaucoma
Except for ocular hypertension detailed above, there are many other factors that may contribute to the development of glaucoma. For instance, glaucoma has been reported to have relation with Alzheimer’s disease that both of these two health problems can be caused by build-up of beta-amyloid. However, people with Alzheimer’s may not have glaucoma. People of African descent are three times more likely to have open-angle glaucoma. Seniors are at a higher risk of developing glaucoma than young and middle-age people, because aging eyes have thinner corneal thickness. Moreover, glaucoma patients will probably transmit the disease to their descendents.
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