Glaucoma is damage to the optic nerve in the back of the eye. Most of the time, but not always, glaucoma is caused by elevated intraocular pressure (IOP) in the eye. Elevated IOP can be caused by many different things including inherited diseases and use of medications such as steroids. Glaucoma can cause permanent loss of vision and often has no symptoms. An estimated 65 million people worldwide have glaucoma, the Glaucoma Research Foundation reports. There are many types of glaucoma.
Open-angle Glaucoma
Open-angle glaucoma is the most common type of glaucoma, affecting about 3 million Americans. This type of glaucoma is often hereditary, is more common in African Americans, and can be age-related. Open-angle glaucoma usually develops as people age, when the ducts that drain fluid from the eye become clogged with cells and debris. The buildup of fluid that results from the ducts being blocked causes the pressure to rise inside the eye.
There are no symptoms to open angle glaucoma at first; eventually, slow, progressive vision loss occurs as pressure is exerted on the sheath that surrounds the optic nerve, compressing the nerve and damaging the nerve cells. Open angle glaucoma is treated with ophthalmic drops that reduce pressure by decreasing the amount of fluid manufactured in the eye or increasing the flow of fluid through the ducts.
Closed-angle Glaucoma
Closed- or narrow-angle glaucoma is a serious medical emergency, the University of Maryland Medical Center warns. If the angle where the iris connects with the eye's drainage ducts suddenly becomes blocked, eye pressure rises quickly. Closed-angle glaucoma is characterized by severe pain in the eye, sudden loss of vision, nausea, headaches and halos or rainbows seen around objects at night, the Glaucoma Research Foundation says. Closed-angle treatment needs immediate medical care or permanent vision loss may occur.
Normal-tension Glaucoma
Normal-tension glaucoma causes damage to the optic nerve even when the eye pressure is within the normal range. A family history of the disease, or a history of heart problems are common in people with normal-tension glaucoma. Damage to the optic nerve can be seen on examination by a medical professional.
Congenital Glaucoma
Congenital glaucoma is a rare disease usually diagnosed before a child is 1-year-old. Congenital glaucoma is often hereditary, caused by a malformation of the canals that drain ocular fluid from the eye. Children with glaucoma can have light sensitivity, eyes that are larger than normal, and a cloudy appearance of the cornea, the membrane that covers the front of the eye.
Secondary Glaucoma
Secondary glaucoma may be caused by drugs that elevate the IOP, such as steroids, or by inflammation in the eye. Diseases such as diabetes can also cause elevated IOP, as can trauma or injury to the eye.
