Glaucoma is one of the leading causes of adult blindness in the United States after AMD (age-related macular degeneration) it is the second most common cause resulting in vision loss. Around 2.2 million Americans age 40 and above have the glaucoma, and, as the condition does not express any symptoms in its primary stages, half of them unaware of the disease. According to researchers 5 to 10 million people are at high risk for the glaucoma
Types of glaucoma
- Open-angle glaucoma: It contributes in almost 90 % of all glaucoma cases reported in the United States, develops slowly and don’t mention any superficial symptoms until reach to later stages.
- Closed-angle glaucoma: It occurs mostly in people of Chinese ancestry and few other Asian groups. The difference between open-angle and closed-angle glaucoma is ended by examining the front portion of the eye to test the angle where the iris meets the cornea. Both types can result in blindness by destructing the optic nerve. Even people with normal IOP can experience damage to the optic nerve. In fact, 25 to 30 percent of people suffer glaucoma do not have imminent interocular pressure (IOP) levels.
Causes of Glaucoma
The eye produces about one teaspoon of aqueous humor each day, a transparent fluid that provides nutrients to, and take away waste products of the lens and cornea. Normally, fluid production and drainage are in equilibrium, and IOP is in-between 12 and 22 mm Hg.
People with open-angle glaucoma have higher than the normal IOP levels Ophthalmologists think that a fractional blockage traps the aqueous humor. Exactly how this occurs is still unknown. As excessive aqueous humor is produced than required, the obstacle causes elevation in IOP. When increased IOP persists or continues to rise, an optic fiber in the nerve is squashed and eventually dies, leading to a progressive loss of eye vision.
In some cases, normal level of IOP is enough to produce optic nerve damage. These people may have thinner cornea than the normal that make IOP measurements turn up to be lower than actual value. The American Academy of Ophthalmology has recommended that people with risk factors for glaucoma e.g. advanced age, elevated IOP, and African-American ancestry; have to measure their corneal thickness.
Closed-angle glaucoma happens due to blockage of aqueous humor at the pupil, cause bowing forward of the iris. This blockage of outflow of aqueous humor consequently increase IOP that can suddenly get worse and lead to severe, permanent vision loss within a couple of days if left untreated.
Aqueous humor -a fluid that transport materials to and from, the lens and cornea-flows behind the iris passing through the pupil into the front cavity of the eye; then it drains through a spongy network of connective tissue called the Trabecular meshwork, where it enter into bloodstream. An alternate system also works known as, the Uveoscleral pathway and is located at the back of the trabecular meshwork.
People with open-angle glaucoma that have higher IOP than normal levels, ophthalmologists assume that a partial blockage of the trabecular meshwork traps the aqueous humor. As supply of aqueous humor is continuous, blockage causes an increase in IOP level. This pressure deteriorates optic nerves and cause vision loss.
Closed-angle glaucoma occurs by a blockage of aqueous humor at the sight of pupil, leading to a bowing forward of the iris that prohibits aqueous humor from reaching the trabecular meshwork. Outflow blockage of aqueous humor results in a sudden raise in IOP that can lead to severe vision damage.
The risk of glaucoma depends upon race and age. This is more common in blacks and Hispanics as compare to whites, and its occurrence increase with age. According to the study, the prevalence of glaucoma was almost one percent in people ages 40 to 49; in those over age 70, it reached up to 10 percent in whites and 20 percent in blacks. Inheritance may play a role in glaucoma risk; mutations causing glaucoma have been recognized.
Corticosteroids mostly used in asthma inhalers and nasal sprays, corticosteroids seem to raise the risk of increased intraocular pressure (IOP) and open-angle glaucoma, conceivably by inhibiting the drainage of aqueous humor. People who use corticosteroids should have their IOP and vision monitored on regular basis.
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