Understanding Glaucoma

Glaucoma is a serious eye condition that can lead to vision loss and can even cause blindness. The condition damages the optic nerve, which is responsible for carrying visual information from the eye to the brain. Glaucoma is the result of high fluid pressure inside the eye. In many cases, it causes no symptoms in its early stages, so people do not realize they have a vision problem. Fortunately, early detection and treatment can slow the progression of vision loss.

Glaucoma is very common, affecting about 3 million people in the United States, according to the Centers for Disease Control and Prevention (CDC). It is the leading cause of blindness in people aged 60 and older, according to the American Academy of Ophthalmology (AAO). It is also the second leading cause of blindness overall.


Researchers have not determined the exact cause of glaucoma. The condition may develop because eye’s drainage system can become inefficient over time. Inadequate blood supply to the optic nerve may also play a role in the development of glaucoma.

There are two main forms of glaucoma: primary open-angle and acute-angle. There are other types such as secondary glaucoma which develops as the result of another illness, for example. Normal-tension glaucoma is a condition in which people have optic nerves that are overly sensitive to normal eye pressure.

Primary open-angle glaucoma

Primary open-angle glaucoma is the most common type. It typically begins slowly and without any symptoms, so people don’t realize they have the condition until they have already suffered vision loss.

This type happens when the eye does not drain well, somewhat like the clogged drain of a sink. Poor drainage causes the pressure inside the eye to rise; this excess pressure damages the optic nerve.

The condition starts very slowly and usually begins by affecting side vision, also known as peripheral vision. Vision loss can spread to central vision needed for reading and other close-up work. Left untreated, it can lead to significant loss in both eyes. Untreated glaucoma may also lead to blindness.

Acute angle-closure glaucoma

Acute angle-closure glaucoma, also known as narrow-angle or closed-angle, is less common. While glaucoma can be a chronic condition that develops slowly, it usually occurs suddenly after an abrupt rise in pressure inside the eye. Acute angle-closure is an emergency condition that requires immediate care from an optometrist.

This type usually happens when someone’s iris, which is the colored part of the eye, sits very close to the drainage angle. The iris can block the drainage angle, somewhat like a flat piece of paper sliding over the drain of a sink. When the drain is completely blocked, the pressure inside the eye rises very quickly. Eye care professionals refer to this as an “acute attack,” as it is a true eye emergency that may lead to blindness. While an acute attack often affects only one eye, the other eye is at increased risk of an attack as well.


Symptoms of acute angle-closure glaucoma can include:

  • Severe eye pain
  • Redness in the eye
  • Blurred vision
  • Seeing colored rings or halos around lights
  • Nausea
The halo effect around light sources caused by Glaucoma. eSight glasses for the visually impaired can help with these side effects.
Often people living with Glaucoma will see a halo effect around light sources

Risk Factors

Certain factors increase the risk, including:

  • Being over the age of 40
  • Having family members with the condition
  • Having African, Hispanic, or Asian heritage
  • High eye pressure
  • Being farsighted or nearsighted
  • A history of eye injury
  • The use of long-term steroid medications
  • Corneas that are thin in the center
  • Thinning of the optic nerve
  • Diabetes, high blood pressure (hypertension), migraine headaches, poor blood circulation or other health problems affecting the whole body

Support and Aids

There is currently no cure for glaucoma, which means vision lost to glaucoma cannot be restored. Early detection and prompt treatment can help preserve vision, however, and prevent further vision loss.


The American Optometric Association recommends that people at risk for glaucoma undergo an annual dilated eye exam.

The typical eye exam for glaucoma includes measurement of the pressure inside the eye, inspection of the eye’s drainage angle, examination of the optic nerve for signs of damage, testing peripheral vision, measurement of the optic nerve.


Medication or surgery can prevent or slow the progression of vision loss. There are a number of eye drop medications for glaucoma, including alpha agonists, beta-blockers and carbonic anhydrase inhibitors that reduce the amount of fluid produced by the eye. Micotic eye drops make the pupil smaller, which lowers eye pressure by increasing the amount of fluid that drains from the eye.

Laser surgery helps drain excess fluid from the eyes. Eye surgeons perform trabeculoplasty to help patients with open-angle glaucoma and iridotomy to help those with angle-closure glaucoma.


Glaucoma is a vision-robbing condition that can prevent people from leading full, independent lives. Fortunately, technological advances have produced a new generation of low vision aids that can enable people to see.

Advanced low vision aids, such as eSight, combine the power of high tech cameras, smart algorithms and high-resolution screens to create sharp, real-time images.

Learn more about diabetic retinopathy.

Skip to content