There are several types of glaucoma. The two main types are open-angle and angle-closure. These are marked by an increase of intraocular pressure (IOP), or pressure inside the eye.
This is the most common form of glaucoma, affecting about three million Americans. It happens when the eye’s drainage canals become clogged over time.
The inner eye pressure (also called intraocular pressure or IOP) rises because the correct amount of fluid can’t drain out of the eye. With open-angle glaucoma, the entrances to the drainage canals are clear and should be working correctly. The clogging problem occurs further inside the drainage canals, similar to a clogged pipe below the drain in a sink.
Most people have no symptoms and no early warning signs. If open-angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. This type of glaucoma develops slowly and sometimes without noticeable sight loss for many years. It usually responds well to medication, especially if caught early and treated.
This type of glaucoma is also known as acute glaucoma or narrow angle glaucoma. It is much more rare and is very different from open-angle glaucoma in that the eye pressure usually rises very quickly.
This happens when the drainage canals get blocked or covered over, like a sink with something covering the drain.
With angle-closure glaucoma, the iris is not as wide and open as it should be. The outer edge of the iris bunches up over the drainage canals, when the pupil enlarges too much or too quickly. This can happen when entering a dark room.
A simple test can be used to see if your angle is normal and wide or abnormal and narrow.
Symptoms of angle-closure glaucoma may include headaches, eye pain, nausea, rainbows around lights at night, and very blurred vision.
Also called low-tension or normal-pressure glaucoma, in normal-tension glaucoma the optic nerve is damaged even though the pressure in the eye is not very high. Doctors do not know why some people’s optic nerves are damaged even though they have almost normal pressure levels.
Those at higher risk for this form of glaucoma are:
- People with a family history of normal-tension glaucoma
- People of Japanese ancestry
- People with a history of systemic heart disease such as irregular heart rhythm.
Early detection, through regular and complete eye exams, is the key to protecting your vision.