What is Glaucoma?

During a dilated eye exam, the doctor will examine and test your eyes to determine if a diagnosis is needed.


This is the most common form of glaucoma and occurs when the trabecular meshwork of the eye gradually becomes less efficient at draining fluid.  As this happens, your eye pressure (intraocular pressure IOP) rises, leading to damage of the optic nerve.  Damage to the optic nerve can occur at different eye pressures in different patients.  There is no ‘right’ eye pressure for everyone.  Your ophthalmologist will establish a target eye pressure for you that he or she predicts will protect your optic nerve from further damage.  Different patients have different target pressures.

With open-angle glaucoma, there are typically no symptoms in the early stages.  As the optic nerve becomes more damaged, blank spots begin to appear in your field of vision.  The blind spots usually go unnoticed until significant damage is done the optic nerve.  If all the optic nerve fibers die, you will be blind.

Since eye pressure rises and falls from day to day and hour to hour, the first examination may not reveal the high eye pressure.  In addition to routine eye pressure testing, it is essential that the optic nerve be examined by an ophthalmologist for proper diagnosis.


Eye pressure is expressed in millimeters of mercury (mmHg), the same unit of measurement used in weather barometers.

Although “normal” eye pressure is considered a measurement less than 21 mmHg, this can be misleading. Some people have a type of glaucoma called normal-tension, or low-tension glaucoma. Their eye pressure is consistently below 21 mmHg, but optic nerve damage and loss of vision still occur. People with normal-tension glaucoma are usually treated in the same way as people who have open-angle glaucoma.


This type happens when someone’s iris is very close to the drainage angle in their eye. The iris can end up blocking the drainage angle. You can think of it like a piece of paper sliding over a sink drain. When the drainage angle gets completely blocked, eye pressure rises very quickly. This is called an acute attack and is a true medical emergency.  Call your ophthalmologist right away or you might go blind. People of Asian descent and those with hyperopia (farsightedness) tend to be more at risk for developing this form of glaucoma.

Symptoms of an acute attack include:

·         Your vision is suddenly blurry

·         You have severe eye pain

·         You have a headache

·         You feel sick to your stomach (nausea)

·         You throw up (vomit)

·         You see rainbow-colored rings or halos around lights

A closed-angle glaucoma attack is a medical emergency and must be treated immediately. Unfortunately, people at risk for developing closed-angle glaucoma often have few or no symptoms before the attack.

People at risk for closed-angle glaucoma should avoid over-the-counter decongestants and other medications where the packaging states not to use these products if you have glaucoma. These products are usually safe to use once your narrow angle has been treated with laser iridotomy but always ask your ophthalmologist if it is safe for you to use products with this warning..


Congenital glaucoma is a rare type of glaucoma that develops in infants and young children and can be inherited. While less common than the other types of glaucoma, this condition can be devastating, often resulting in blindness if not diagnosed and treated early.


This form of glaucoma results from another eye condition or disease.  If someone has had an eye injury, on long-term steroid therapy, of has a tumor, may develop secondary glaucoma.  The most common forms of secondary glaucoma are: pseudoexfoliative glaucoma, pigmentary glaucoma, and neovascular glaucoma.


Some people have normal eye pressure but their optic nerve or visual field looks suspicious for glaucoma. These people must be watched carefully because some eventually develop definite glaucoma and need treatment.

Other people have an eye pressure that is higher than normal, but they do not have other signs of glaucoma, such as optic nerve damage or blank spots that show up in their peripheral (side) vision when tested. This condition is called ocular hypertension. Individuals with ocular hypertension are at higher risk for developing glaucoma compared to people with lower, or average, eye pressure. Just like people with glaucoma, people with ocular hypertension need to be closely monitored by an ophthalmologist to ensure they receive appropriate treatment.