High intraocular pressure and glaucoma

Sunday, November 15th, 2009 at 4:24 pm Post in Eye Diseases

Glaucoma patients have an imbalance between the production and drainage of internal fluids in the eye. These internal fluids are essential to maintain a normal intraocular pressure (IOP) so that the eye can stay 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, resulting in high IOP. High IOP will push and damage optic nerve and then vision loss can be caused.

There is underlying reason that why glaucoma always brings high IOP. It involves the internal structure of the eye and the way 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 firstly flow behind the iris and through the pupil, and then fill the anterior chamber. Later, eye fluids pass through the filtration angel and flow through the sclera and then join with the outside network. In this process, the filtration angle is critical in maintaining normal IOP. Once eye fluids can not pass through it, IOP builds up. By narrowing the filtration angle or damaging the angle’s internal tissues, glaucoma hinders the outflow of eye fluids.

Glaucoma does not bring high IOP certainly and one 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.

Since not all types of glaucoma bring 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. The most ensuring way is to examine the optic nerve directly, such as using a visual field testing.

Glaucoma has been reported to have relation with Alzheimer’s that both of them can be caused by beta-amyloid built-up. Nevertheless, people with Alzheimer’s may not have glaucoma.