Glaucoma is a group of eye diseases, and each type is different. The two most common forms are open-angle glaucoma, and closed-angle glaucoma.
These two types of glaucoma in particular have several things in common:
- High eye pressure is the greatest risk factor
- They are most often characterized by damage to the optic nerve.
- People with glaucoma experience gradual vision loss, initially as a loss of peripheral vision.
- Often, symptoms are unnoticeable early on.
There are also some important differences:
- Open-angle is usually a chronic condition with few symptoms, while closed-angle is most often an acute condition with sudden symptoms.
- In open-angle, eye pressure builds gradually, but in closed-angle, it’s far more sudden.
- Open-angle glaucoma is not a medical emergency, but can cause vision issues over time; closed-angle is a medical emergency requiring immediate medical attention.
The dangers of high intraocular pressure
High eye pressure is as troublesome as high blood pressure when it comes to our health. Statistically speaking, those with high eye pressure, also known as intraocular pressure (IOP), often have other health issues, as well, including high blood pressure and diabetes.
Eye pressure can increase as a result of age, certain medications, and eye trauma. It also tends to run in families, and African Americans are at greater risk.
Left untreated, high eye pressure (which is greater than 21mmHg, or millimeters of mercury) can trigger the development of glaucoma, particularly the open-angle or closed-angle types.
Where does the term “angle” come from?
There’s an angle between the iris (the colored part of your eye) and the cornea (the transparent covering over your eye). It’s in the location of this angle where the fluid produced inside your eye (called the aqueous humor) drains from the eye into the body’s circulatory system. This aqueous humor helps maintain the right eye pressure.
A sponge-like structure inside the eye called the trabecular meshwork is important for that drainage function to work correctly. The fluid drains through the trabecular meshwork, then through a drainage canal, into collector channels and then to veins.
One of the reasons aging puts us at higher risk for high eye pressure is that as we get older, we lose the trabecular cells that help the meshwork do its important work. As a result, fluid can build up inside the eye.
What is open-angle glaucoma?
This is the most common form of glaucoma, found in 90% of people with the disease. While experts don’t know for sure what causes this type, many agree that as pressure in the eye builds, it increasingly pushes on the optic nerve, resulting over time in impaired vision.
Vision loss may be so gradual that you may not notice any symptoms of this chronic disease. This is one reason regular eye exams are so important, especially if you have one or more risk factors. Because open-angle is a chronic condition, your eye doctor will need to conduct specific diagnostic tests to measure your eye pressure and to confirm how wide open the drainage angle is between the iris and the cornea.
What is closed-angle glaucoma?
Also called angle-closure glaucoma or narrow-angle glaucoma, this type is a medical emergency requiring an immediate trip to the emergency room or your eye doctor. The aqueous humor is blocked completely from draining out of your eye, causing a sudden spike in eye pressure. When this type of glaucoma occurs, it can lead to blindness in a matter of days if left untreated.
Sometimes angle-closure glaucoma does occur more gradually and without symptoms, but most often it’s acute angle-closure glaucoma that should be treated right away. These symptoms include:
- Severe and throbbing eye pain
- Red eyes
- Blurred vision
- Nausea and vomiting
Are you at risk of glaucoma? Regular eye exams are important for everyone, and especially for those who are at risk of developing certain eye diseases. Protect your vision by scheduling an eye exam today.