Glaucoma has been called the “silent thief of sight” because the loss of vision often occurs gradually over a long period of time, and symptoms only occur when the disease is quite advanced. Glaucoma is an eye disease in which the optic nerve is damaged due to the loss of retinal ganglion cells in a characteristic pattern. Raised intraocular pressure (above 21 mmHg) is the most important and only modifiable risk factor for glaucoma. However, some may have high eye pressure for years and never develop damage, while others can develop nerve damage at a relatively low pressure. Without glaucoma surgery or other management, the disease can lead to permanent damage of the optic nerve and resultant visual field loss, which over time can progress to blindness.
Glaucoma can be roughly divided into two main categories, “open angle” and “closed angle” (or “angle closure”) glaucoma. The angle refers to the area between the iris and cornea, through which fluid must flow to escape via the trabecular meshwork. Closed angle glaucoma can appear suddenly and is often painful; visual loss can progress quickly, but the discomfort often leads patients to seek medical attention before permanent damage occurs. Open angle, chronic glaucoma tends to progress at a slower rate and patients may not notice they have lost vision until the disease has progressed significantly. Once lost, vision cannot normally be recovered and so surgery or other treatment is aimed at preventing further loss.
Worldwide, glaucoma is the second leading cause of blindness after cataracts. It is also the leading cause of blindness among African Americans. Glaucoma affects one in 200 people aged fifty and younger, and one in 10 over the age of eighty. If the condition is detected early enough, it is possible to arrest the development or slow the progression with glaucoma surgery or other management treatment.