What is Angle-closure glaucoma?
Glaucoma is a term describing a group of ocular (eye) disorders that result in optic nerve damage, often associated with increased fluid pressure in the eye (intraocular pressure) (IOP). The disorders can be roughly divided into two main categories, "open-angle" and "closed-angle" (or "angle closure") glaucoma. Open-angle chronic glaucoma is painless, tends to develop slowly over time and often has no symptoms until the disease has progressed significantly. It is treated with either glaucoma medication to lower the pressure, or with various pressure-reducing glaucoma surgeries. Closed-angle glaucoma, however, is characterized by sudden eye pain, redness, nausea and vomiting, and other symptoms resulting from a sudden spike in intraocular pressure, and is treated as a medical emergency.
Glaucoma can permanently damage vision in the affected eye(s), first by decreasing peripheral vision (reducing the visual field), and then potentially leading to blindness if left untreated.
The many different subtypes of glaucoma can all be considered to be a type of optic neuropathy. The nerve damage involves loss of retinal ganglion cells in a characteristic pattern. Raised intraocular pressure (above 21mmHg) is the most important and only modifiable risk factor for glaucoma. Some may have high eye pressure for years and never develop damage, a condition known as "ocular hypertension". Conversely, the term 'low tension' or 'normal tension' glaucoma is used for those with optic nerve damage and associated visual field loss, but normal or low intraocular pressure.
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. Once lost, vision cannot normally be recovered, so 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 50 and younger, and one in 10 over the age of 80. If the condition is detected early enough, it is possible to arrest the development or slow the progression with medical and surgical means.
The word "glaucoma" comes from the Greek γλαύκωμα, a derivative of γλαυκóς, which commonly described the color of eyes which were not dark (i.e. blue, green, light gray). Eyes described as γλαυκóς due to disease might have had a gray cataract in the Hippocratic era, or, in the early Common Era, the greenish pupillary hue sometimes seen in angle-closure glaucoma. In English, the term "glaucoma" was not commonly used until after 1850, when the development of the ophthalmoscope permitted visualization of the optic nerve damage caused by glaucoma.