Types of Glaucoma
Glaucoma is a disease characterized by elevated intraocular pressure that results in damage to the optic nerve. There are several different types of glaucoma, including open-angle, closed-angle, normal-tension, congenital, and acute glaucoma.
The most common form of the disease, open-angle glaucoma affects approximately three million Americans. Open-angle glaucoma occurs when fluid drains too slowly from the angle between the iris and the cornea. The fluid builds up and causes elevated intraocular pressure (IOP), which, if left untreated, will lead to optic nerve damage and eventual blindness. Fluid buildup can also occur if the eye produces excess fluid.
Open-angle glaucoma generally starts in one eye, but over time will eventually move into the other eye. Treatment for this condition most often involves the use of oral and/or topical medication. For individuals who do not respond to medication, glaucoma surgery may be recommended. Open-angle glaucoma can be primary (occurring for no known reason) or secondary (occurring due to previous illness or injury).
Closed-angle glaucoma, also known as angle-closure glaucoma, is a rare form of the disease that accounts for approximately 15 percent of all glaucoma cases in the United States. This type of glaucoma occurs when a portion of the iris blocks the drainage angle. Fluid pressure builds up and must be lowered to prevent damage to the eye. Symptoms may include blurred vision, headache, severe eye pain, halos, nausea, and vomiting. If the condition develops gradually, however, no symptoms may be apparent. Closed-angle glaucoma is more prevalent in Asian populations, and it often occurs when the pupil dilates suddenly. This condition can be primary (occurring for no known reason) or secondary (occurring due to previous illness or injury).
A form of closed-angle glaucoma known as acute glaucoma occurs when the eye rapidly experiences a substantial increase in IOP. Acute glaucoma requires the immediate medical attention of a glaucoma specialist in order to prevent permanent vision loss.
Normal-tension glaucoma, also referred to as low-tension glaucoma or normotensive glaucoma, accounts for approximately 25 to 30 percent of all glaucoma cases in the United States. This type of glaucoma is not associated with elevated intraocular pressure. Patients with this type of glaucoma have normal IOP but some level of optic nerve damage. Find out about the causes of normal-tension glaucoma.
Congenital glaucoma occurs at birth as a result of the drainage canals not forming properly. Infants with congenital glaucoma are often sensitive to light and have cloudy corneas. This is a rare form of glaucoma that can usually be treated with surgery. Because children often cannot recognize the symptoms of this condition, a glaucoma specialist may be needed to detect its presence.
Acute glaucoma is closely related to angle-closure glaucoma. This condition, also known as acute closed-angle glaucoma, occurs when the iris prevents intraocular fluid from draining properly, creating a large and sudden increase in IOP. Symptoms include headache, intense eye pain, blurred vision, nausea, vomiting, and halos. Acute glaucoma is often the result of pupil dilation, which can occur in low light situations or after the use of dilating eye drops or certain medications, such as antihistamines and cold medicines.
Other Types of Glaucoma
In addition to the forms of glaucoma mentioned above, several rare types of glaucoma also exist. A glaucoma specialist can detect the presence of these unusual forms of the disease:
- Pigment glaucoma: Flakes of pigment from the iris get into the eye fluid and block the drainage angle.
- Pseudoexfoliation syndrome: Tiny flakes from the outside of the lens collect in the drainage angle and obstruct fluid flow.
- Irido corneal endothelial syndrome (ICE): Cells from the back surface of the cornea form scars that connect the iris to the cornea and block the drainage angle.
- Neovascular glaucoma: The formation of blood vessels on the iris and drainage angle that block the flow of fluid (usually associated with other disorders, such as diabetes).
Often asymptomatic at its onset, glaucoma may be undetectable until vision is impaired. Affecting peripheral vision first, if glaucoma is left untreated, vision loss may continue to progress, eventually resulting in total blindness.
At the onset of open-angle glaucoma, no symptoms are evident. Vision stays normal and there is no pain. Frequent, routine eye examinations are the best way to detect glaucoma. The results of these periodic evaluations are compared at regular intervals to determine if glaucoma progression has occurred. Learn more about glaucoma tests and diagnosis.
Loss of Peripheral Vision
Although glaucoma progression may or may not exhibit distinct symptoms, without early treatment, vision loss is almost inevitable. Generally, glaucoma progression begins at the peripheral vision, the part of vision that occurs outside the very center of gaze; however, glaucoma can also affect central vision. Early vision loss is often subtle and may go unnoticed. Moderate to severe vision loss may be noticed by an optometrist or ophthalmologist during an exam. Often, glaucoma is undetected until the patient experiences tunnel vision. Waiting for discernable vision loss symptoms to occur is not the optimal method of care. Glaucoma is incurable, but progression can be prevented or slowed by glaucoma treatment.
Glaucoma progression can worsen vision, and if left untreated, total vision loss may occur. Despite effective advancements in the treatment of glaucoma, vision lost to the disease is permanent. Medications and surgery have been effective in slowing glaucoma progression, but there is no cure. Diagnosing glaucoma as early as possible is key to countering eventual blindness. Routine vision exams are recommended, especially for individuals over the age of 40 who are at a higher risk for glaucoma.
Contact a Doctor
Recent advances in medical technology have led to significant improvements in glaucoma treatment. If you would like to schedule a consultation with a glaucoma specialist, DocShop can provide you with a list of qualified practitioners in your area.