The 4 Types of Glaucoma
The aqueous humor is a clear, transparent liquid that continually circulates throughout the eye. When this circulation becomes restricted for one reason or another, pressure inside the eye begins to rise. Typically, there are four general types of glaucoma:
- Chronic open-angle glaucoma
- Angle-closure glaucoma
- Congenital glaucoma
- Secondary glaucoma(s)
Chronic Open-Angle Glaucoma
By far the most common type of glaucoma, chronic open angle glaucoma, occurs when the exit of aqueous humor from the eye is restricted by inadequate drainage. Chronic open-angle glaucoma develops slowly over a long period of time and results in the quiet loss of vision, because no symptoms occur until the optic nerve is extensively and permanently damaged.
If the front of the eye, or the angle between the iris and cornea, is narrow or crowded, pressure inside the eye may rise chronically or suddenly. This chronic or sudden blockage of the eye’s outflow system is called narrow angle or angle-closure glaucoma. Patients may or may not complain of blurred vision or halos around lights, severe pain, nausea and vomiting. Unless the pressure is brought under control rapidly, complete blindness may result in a very short time.
If the outflow system of the eye exhibits abnormalities from the time of birth, congenital glaucoma may result. Infants born with glaucoma may be extremely sensitive to light and tear excessively, or the front of the eye may be enlarged or cloudy. Fortunately, this condition is uncommon. An eye examination is advised even for newborns if such symptoms are noted.
Glaucoma may result from trauma or injury, diabetes, or previous stroke in the eye, or may happen as a result of certain medications or inflammation. These are all conditions which may lead to blockage of aqueous drainage from the eye and high intraocular pressures.