Glaucoma is a term used for a group of eye diseases that affects the optic nerve in various stages depending upon the intraocular pressure in the eye. According to the Glaucoma Research Foundation, more than 4 million people in United States are affected with glaucoma but only half of them show any signs or symptoms of it. Approximately 10 percent of individuals receiving treatment still experience a loss in vision over time.
Causes
The liquid aqueous humor circulates throughout the eye and gets drained through the eye's drainage system of ducts. These tiny channels are at an angle created by the iris, cornea and the white of the eye. If there is any blockage or obstacle, the pressure increases within the eyeball, leading to increased compression on the optic nerve. Typically blockages occur from the narrowing of these channels. It remains unknown as to why these channels narrow.
With time, the blood circulation to the optic nerve is lowered due to the intraocular pressure, and that causes damage to the optical nerve cells. The nerves and tissue become weak and damage the core of the optic nerve, leading to blind spots in most cases and blindness if ignored.
Types
The variations in the intraocular pressure lead to a variety of different levels and types of glaucoma. The most common is open angle glaucoma, when the fluid does not get drained but accumulates in the filtration tissues and builds pressure. If untreated, it leads to blindness.
Chronic angle-closure glaucoma causes sudden vision loss and is usually without symptoms. Age and family history of glaucoma are the main reasons for this type, while older women are affected more than men.
Acute angle-closure glaucoma is a rapid buildup of intraocular pressure leading to noticeable symptoms such as blurred vision, headache, severe eye pain, nausea and vomiting.
Hereditary glaucoma typically starts in infancy or early childhood and at least one or more family members suffer from this disease. There are typically no symptoms. Congenital glaucoma usually occurs at birth or within the first year but there is no family history or clear cause for this disease. Common symptoms are light sensitivity, tearing and cornea cloudiness.
Low-tension glaucoma is a rare type of glaucoma where the optic nerve is damaged but the intraocular fluid pressure is normal or low.
Symptoms
Primary open-angle glaucoma and acute angle-closure glaucoma are the most common forms of the disease and have different sets of symptoms. Most common signs and symptoms of primary glaucoma are slow loss of peripheral vision in early stages and tunnel vision in later stages. The common symptoms of acute angle-closure glaucoma are severe eye pain accompanied by vomiting and nausea, blurred vision, halos around objects, sudden visual disturbances in dim light and reddish eyes. In secondary glaucoma, the onset maybe due to injury, diabetes, hypertension, advanced cataracts or inflammation in the iris. The symptoms are similar.
Risk Factors
Asians, African Americans and everyone over the over the age of 60 years are at a high risk of developing glaucoma, according to the Glaucoma Research Foundation. If the intraocular pressure is high, you are at a risk of developing this disease. Injury, diabetes and hypertension and genetic or family history are some of the leading causes of glaucoma.
People with a family history of glaucoma are categorized as high risk because they have a defective genetic link that causes the person to be susceptible to developing the disease early. Juvenile glaucoma is generally linked to chromosome defects.
Diagnosis
There are specific tests that are done to correctly diagnose glaucoma. Tonometry is a painless, simple test that gauges the ocular pressure and is the basic test for screening. It uses a contact probe or a puff of air to determine how much pressure it takes to flatten part of the cornea. The optic nerve damage test is used to check the cells and tissue of the optic nerve for determining the stages of glaucoma. Other tests that help determine the intensity and other details are pachymetry, which checks the thickness of the cornea; gonioscopy, which checks if the drainage angle is open or closed; and tonography, which determines the level of blockage, drainage and speed of fluid drain from the eye.
