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Glaucoma is a commonly misunderstood disease. According to the Glaucoma Research Foundation, over three million Americans have glaucoma but only half of those know they have it. DocShop has compiled the following information as an educational resource, and can help you locate a glaucoma specialist near you. Find answers to frequently asked questions: What is glaucoma? What are the symptoms or signs of glaucoma? And examine the treatments available for glaucoma.

What Is Glaucoma?

Glaucoma is a disease of the eye that damages the optic nerve. Glaucoma can cause blindness and is, in fact, the leading cause of blindness. Contrary to what many people believe, glaucoma is not a disease that is limited to the elderly. The condition can appear in children and young adults as well. Glaucoma may occur when the natural fluids of the eye are impeded from draining properly, causing intraocular pressure (IOP) to build. Over time, this elevated IOP may damage the optic nerve, leading to the development of glaucoma. Other causes of glaucoma depend on the specific type of glaucoma a person develops.

General Risk Factors & Causes for Glaucoma

Certain people are at a heightened risk of developing glaucoma. These include:

  • African-Americans over 40 years of age
  • People who have a family history of glaucoma
  • Steroid users
  • People with prior ocular injuries
  • Patients with ocular hypertension
  • People over 60 years of age

There are also several medical conditions that increase a person’s risk of glaucoma, including:

  • Diabetes
  • Hypothyroidism
  • Leukemia
  • Sickle cell anemia
  • Arthritis

Learn more about the symptoms of glaucoma.

Causes of Open-Angle Glaucoma

The most common form of glaucoma, open-angle glaucoma, affects approximately three million Americans. Causes of open-angle glaucoma include:

  • Aging - The aging process reduces the size of the eye’s drainage angle, resulting in increased intraocular pressure.
  • Genes - Several genetic factors can contribute to glaucoma. Mutations in the GLC1A gene cause it to overproduce a substance that clogs the angle where fluid drains from the eye. In addition, the LMX1B gene is believed to cause some cases of glaucoma.
  • Nitric oxide deficiencies - Low levels of nitric oxide contribute to unhealthy blood vessels, which in turn elevate intraocular pressure.
  • Nutritional deficiencies - This may cause damage to optic nerve fibers.
  • Brain chemical abnormalities - Large amounts of glutamate (a neurotransmitter) can contribute to the destruction of nerve fibers within the eye.

Open-angle glaucoma does not typically present symptoms in its early stages. However, eventually the patient will begin to lose his or her peripheral vision.

Causes of Closed-Angle Glaucoma

Closed-angle glaucoma, a rare form of the disease accounting for just 15 percent of all glaucoma cases in the country, is caused by a structural defect within the eye that creates a narrow angle between the iris and cornea. If the iris slips forward, it may block the fluid drainage angle. This condition can be triggered by medications that dilate the pupil, such as antihistamines and tricyclic antidepressants. It can also occur naturally, when the eye dilates in low light. People who suffer from hyperopia (farsightedness) are at a heightened risk for acute closed-angle glaucoma because their eyes have narrow drainage angles. Closed-angle glaucoma produces symptoms of severe eye pain, blurred or haloed vision, nausea, vomiting, and headache.

Causes of Normal-Tension Glaucoma

Since elevated IOP is not a factor in normal-tension glaucoma, doctors are not sure what causes optic nerve damage. Theories include:

  • Reduced blood flow
  • Early nerve cell death
  • Nerve irritation
  • Excess glutamate production
  • Autoimmune disease

Normal-tension glaucoma may result in a loss of peripheral vision.

Causes of Congenital Glaucoma

Congenital glaucoma is present at or near the time of birth. Typical causes of congenital glaucoma include genetic defects in the drainage canal or other existing eye conditions. Approximately 85 percent of congenital glaucoma cases can be attributed to an inherited genetic defect. Congenital glaucoma is referred to as infantile when it is present within the first three years of life and juvenile if it occurs after three years of age. Studies have shown that congenital glaucoma affects male children more often (65 percent) than females. Congenital glaucoma occurs bilaterally (in both eyes) in 70 percent of studied cases. Congenital glaucoma can be difficult to recognize because children often have trouble discerning the symptoms.

Causes of Secondary Glaucoma

Secondary glaucoma is associated with a previous illness, injury, or disease. There are many secondary causes of glaucoma. Secondary glaucoma can be either of the open-angle or closed-angle variety, and are associated with:

  • Developmental glaucoma, as in neurofibromatosis
  • Ocular disease – pigment dispersion and neovascular glaucoma
  • Systemic diseases and drugs – corticosteroid glaucoma
  • Inflammation – uveitis
  • Trauma – angle recession, RBC associated glaucoma
  • Ocular surgery – aphakic glaucoma, aqueous misdirection

Signs and Symptoms of Glaucoma

Symptoms or signs of glaucoma are often absent in the earliest stages of the disease. Tragically, impaired vision is sometimes the first sign of glaucoma. In other instances, symptoms and signs of glaucoma may include eye pain, clouded or haloed vision, red eyes, headaches, and nausea. Learn more about the symptoms of glaucoma.

How Is Glaucoma Detected?

Open-angle glaucoma, the most common form of the disease, is often referred to as the "silent thief of sight" because it presents no physical symptoms until the first signs of vision loss. Only preventive glaucoma diagnosis and treatment can effectively preserve vision. This is why it is important to have annual eye exams that include a glaucoma test to check intraocular pressure. Early detection is the key to protecting your vision from damage caused by glaucoma. The Glaucoma Research Foundation recommends that you eyes should be tested at:

  • Ages 35 and 40
  • From age 40 to age 60 – every two years
  • After age 60 – every year
  • Anyone with high risk factors should be tested every year after age 35.

Glaucoma Exam and Test

Individuals at greatest risk for glaucoma should have their eye doctor perform a comprehensive eye exam and diagnostic glaucoma tests. If glaucoma tests identify the disease in its early stages, it can be managed before severe vision loss occurs. Regular glaucoma check-ups include two routine eye tests: tonometry and ophthalmoscopy. If the pressure in the eye is not in the normal range, or if the optic nerve looks unusual, then one or two special glaucoma tests will be done. These two tests are called gonioscopy and perimetry. The glaucoma test and eye exam includes the following:

Family History

The most common type of glaucoma, primary open angle glaucoma, is hereditary. If members of your immediate family have glaucoma, you are at a much higher risk than the rest of the population. Family history increases risk of glaucoma four to nine times.

Visual Acuity Test

Field of vision changes are one of the first symptoms to surface in glaucoma patients. By the time central vision is affected, glaucoma is already too far advanced with almost all peripheral vision permanently lost. A visual acuity test measures a patient’s ability to see far away or up close. For this test, you may be asked to read from an eye chart. The visual acuity test uses an eye chart with letters and images to measure vision ability at various distances.

Intraocular Pressure Check (Tonometry)

The tonometry test measures the eye’s intraocular pressure (IOP). The test is used in the detection and diagnosis of glaucoma. Usually drops are used to numb the eye before the doctor or technician uses a special device to measure the eye’s pressure. The tonometry test takes only minutes to perform and does not cause any eye pain.

Retinal and Optic Nerve Exam (Ophthalmoscopy)

Ophthalmoscopy is used to examine the inside of the eye, focusing on the retina and optic nerve. In a darkened room, the physician will dilate the pupils before magnifying the patient’s eye using an ophthalmoscope (an instrument with a small light on the end). This allows the physician to look at the shape and color of the optic nerve. If this test reveals an optic nerve that looks unusual, additional glaucoma tests (gonioscopy and perimetry) will be done.

Drainage Angle Inspection (Gonioscopy)

Gonioscopy is a painless eye test that determines whether the area where fluid drains out of your eye (the drainage angle) is open or closed. It is often done during a routine eye examination, depending on your age and whether or not you are at high risk for developing glaucoma. Although the causes of glaucoma are not well understood, if the drainage angle becomes damaged, blocked, or clogged, pressure may increase inside the eye.

Evaluation of the Visual Field (Perimetry)

A perimetry glaucoma test measures all areas of your vision, including your peripheral vision. At the end of the test, a printout shows if there are any areas of vision loss. Loss of peripheral vision is often an early sign of glaucoma. Early detection is key in successful glaucoma diagnosis and treatment.

Glaucoma Types

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.

Open-Angle 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

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

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

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

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).

Glaucoma Progression

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.

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.

Treatment for Glaucoma

There is no cure for glaucoma, but there are treatments for glaucoma, and they fall into two categories: medication and surgery. Both of these treatments for glaucoma manage the disease by lowering the intraocular pressure. Medications and eye drops are common remedies, but there is the possibility of side effects, and they may eventually become ineffective over time. If the IOP cannot be managed by medications or eye drops alone, surgery may be recommended, depending on the type of glaucoma. The surgical goal would be to drain the intraocular fluid by expanding the existing drainage area or by creating a new outlet for the fluids to drain through. 

Recovery after Glaucoma Treatment

Glaucoma surgery is usually painless, although some patients may experience a slight stinging sensation following the procedure. Local anesthetics are used to diminish any patient discomfort. After the surgical treatments for glaucoma, patients may experience blurred vision or irritation. Typically, however, these effects are short-lived and normal activities, such as going to work or running errands, can be resumed the next day. Learn more about recovery and results after glaucoma surgery.

Talk to a Glaucoma Specialist in Your Area

Glaucoma can be a very serious, debilitating disease. It is crucial to visit a glaucoma specialist if you have any signs or symptoms of glaucoma. Find a glaucoma doctor in your area with the assistance of the DocShop directory. DocShop can help you find an experienced doctor who can determine what is causing your glaucoma and provide you with effective treatments for glaucoma.

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