Glaucoma is a disease which affects approximately four million people. Unfortunately, only half the patients with the disease are aware they have it. For this reason, glaucoma is often referred to as the silent thief of sight.
Glaucoma develops when the internal eye pressure (the intraocular pressure) becomes elevated and damages the optic nerve. The optic nerve deteriorates under the stress of the pressure and eventually is no longer able to carry images from the eye to the brain. There is no cure for glaucoma but treatment can slow or prevent its progression, particularly if detected early.
Everyone is at risk for glaucoma; however certain groups are at higher risk. Glaucoma is the leading cause of blindness among African-Americans. Glaucoma affects African-Americans six to eight times more frequently than Caucasians. Age is a major risk factor as well. People over 60 are six times more likely to have glaucoma. Family history for glaucoma is also a major risk factor. Patients with a first-degree relative with the disease are ten times more likely to have glaucoma. Other significant risk factors include Hispanic ancestry, previous steroid use, previous injury, diabetes, hypertension, myopia (near-sightedness), and other anatomic factors of the eye.
There are many types of glaucoma which are usually subcategorized into two classes: open angle and closed angle. Open angle glaucoma is the most common type of glaucoma. In open angle glaucoma, the intraocular pressure is elevated despite the natural drainage angle in the eye being open. The drainage angle is formed between the colored portion of the eye, the iris, and the internal surface of the cornea. This forms an angle where the natural drainage structures (the trabecular meshwork) are located. Open angle glaucoma include many further subtypes of glaucoma including, pseudoexfoliation glaucoma in which dandruff-like particles block the trabecular meshwork. Other forms of glaucoma including neovascular, pigmentary, and traumatic glaucoma are also grouped in this category.
In closed angle glaucoma this drainage area is blocked by the iris bowing forward against the trabecular meshwork. This anatomic configuration may develop slowly leading to chronic angle closure glaucoma. If drainage angle closes suddenly, this may cause an acute attack of glaucoma in which the eye pressure rises rapidly. Acute glaucoma is a medical emergency which requires immediate treatment in order to prevent rapid and permanent visual loss.