What Your Glaucoma Test Results Mean

Your eyes serve as your windows to the world. Without them, living your daily life may become more difficult. That’s why it is important to watch out for diseases that can cause vision loss. One of the leading causes of blindness is glaucoma, a condition that harms the optic nerve cells. Since this eye problem has no noticeable warning signs, early detection and effective treatment of glaucoma require regular eye tests.

The condition develops gradually. However, it can cause irreversible damage to the optic nerve that could result in vision loss or trouble normal daily tasks, such as driving.  You should learn how often you should be tested for glaucoma. 

In general, those older than 40 and have a history of the disease in their family should get checked every one or two years. If you know someone in your family who has glaucoma or a condition that could contribute to the disease, such as diabetes, make sure you have an eye exam annually.

Certain factors warrant more frequent testing for the condition. The following characteristics give you a higher chance of being diagnosed with glaucoma:

  • Corneal thickness – You’re more likely to suffer from glaucoma if your corneal thickness is thinner than average.
    • Family history – Having a history of the disease in your family puts you at a higher risk of developing the disease.
    • Age – People aged 65 or older are more likely to have glaucoma.
    • Race – Those of African-American descent are four times more likely to develop the disease.
    • Eyesight – Nearsightedness also accounts for many glaucoma cases.
  • Health – Diabetes can cause glaucoma.

Understanding test results

You may have to undergo a visual field test to measure your peripheral vision. This is because glaucoma can cause peripheral eyesight loss. There are different ways to perform this exam, but usually, one eye is tested at a time using a unique instrument. 

During the exam, you will be seated in front of a machine. You need to position your head and focus your vision on the light ahead. Expect a faint light to appear momentarily at different angles in your field of vision. Press a button each time you spot the light.

If you find it difficult to identify the flickering lights of various intensities and sizes, you may be a suspect for glaucoma. Worse results over time typically indicate the progression of the disease. Ask your eye doctor to discuss the exam and test results so you know whether you’re suffering from peripheral vision loss. 

Optic nerve photography

Damage to the nerve fiber layer and optic nerve indicate glaucoma. Optic nerve photographs reveal the damage over time. Your eye doctor will investigate these photos to pick out abnormalities and compare the health of the optic nerve in follow-up tests. If something is not right with your optic nerve, you are likely to have glaucoma.

Optic nerve photography is a critical part of glaucoma testing. Elevated eye pressures are not always seen in patients who have a subtype of the disease called normal-tension glaucoma. The clinic will take images of the optic nerve during the patient’s initial examination, then a least every year or more often if there are noticeable changes. 

Optic coherence tomography test

This exam takes a topographical map of the optic nerve, using non-invasive waves that capture cross-section photos of the retina. An OCT exam determines the thickness of the nerve fiber layer, which is the portion of the optic nerve most defenseless to eye pressure elevation. 

The patient will have the OCT test in his or her initial exam and then every six to 12 months after. Damage by elevated intraocular pressure causes thinning of the optic nerve. In addition to glaucoma, OCT is useful in diagnosing other eye diseases such as age-related macular degeneration and diabetic retinopathy.


This is a test doctors use to measure the pressure inside the eyes. Tonometry requires eye drops that anesthetize the eye, while a tiny device touches the eyeball to calculate the amount of eye pressure. The range for normal pressure is 12 to 22 millimeters of mercury (mm Hg), according to the Glaucoma Research Foundation. When the pressure goes over 22 mm Hg, that typically signal an abnormal glaucoma test. Adults with pressure around 16 mm Hg or higher may also suffer from normal-tension glaucoma.

Having various eye exams is crucial because glaucoma is a complex condition. Before deciding on final diagnosis, an eye doctor will consider different glaucoma tests. Intraocular pressure measurements from tonometry are only one set of these tests. 


During this exam, an eye doctor will use eye drops to dilate the pupil. He or she will check your eye with a device that has a light to magnify the optic nerve. If this part’s shape or color doesn’t appear normal, or the pressure within the eye is higher than the normal range, your doctor may perform more tests to double-check the abnormal glaucoma test results. This is essential to be certain of the diagnosis.

Next steps after you have your results

You are likely a glaucoma suspect if your test results indicate elevated IOP. However, to arrive at a glaucoma diagnosis, you must discuss it with your eye doctor. A thick cornea, even with a high IOP, could be artificially high. 

For the sake of your overall eye health as well as for managing glaucoma, your best option is to have an annual eye checkup. Work with a professional who can take note of the changes in your vision over time. 

Your doctor will consider the results of each test you take to determine whether you have the disease. These results also help determine if the illness is progressing and at what stage it is on currently. 

If you want to know what your glaucoma test results mean, consult our experts at Arizona Retinal Specialists. We will also help determine which tests you can expect if you’re still in the discovery phase of your eye care journey. Call us at 623-474-3937 (EYES) to schedule an appointment with an eye doctor today. 


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