Glaucoma Testing

July 29, 2019 — by Thomas Byrd, MD
Tags: Glaucoma

Illustration of glaucoma symptomsGlaucoma is an eye disease that results when excess ocular pressure causes damage to the optic nerve. Glaucoma is a progressive condition that gradually worsens over time. If glaucoma is not diagnosed and treated, it can lead to vision loss, and eventually, total blindness.

At Byrd Eye Clinic in Detroit, MI, we offer comprehensive eye care services, including glaucoma testing, to diagnose eye conditions. Glaucoma does not result in symptoms early on, so by the time a patient notices that his or her vision has changed, glaucoma may have already progressed to the point that permanent damage has developed. Dr. Thomas Byrd offers five types of glaucoma testing that are key to the diagnosis of this disease.


Tonometry is a test that allows Dr. Byrd to measure a patient’s intraocular pressure. The normal range for intraocular pressure is 12 to 22 mm Hg. If patients have higher inner eye pressure, it is likely that they are suffering from glaucoma.

To perform the tonometry test, Dr. Byrd numbs the eye with eye drops. He then applies pressure to the eye using either a small device or a warm puff of air. While pressure is applied, a device called a tonometer measures the eye’s inner pressure.

Because each person’s normal eye pressure is unique, routine exams are important. An increase in eye pressure (even if that eye pressure may not be elevated for another patient) is a good indicator of early stage glaucoma.


Pachymetry is a quick and painless procedure that measures the thickness of the cornea. Dr. Byrd uses a simple probe to take this measurement, and it takes just a couple of minutes for both eyes.

Corneal thickness can affect intraocular pressure for our Detroit patients, so this reading helps Dr. Byrd interpret the readings of the tonometry exam.


An ophthalmoscopy is an examination of the optic nerves. Since glaucoma is known to cause damage to the optic nerve, it is important for Dr. Byrd to look at its shape and color to see if there are any signs of damage.

This exam is performed with the patient’s eyes dilated. Dilating the eyes allows Dr. Byrd to look through the eye and examine the optic nerve at the back. Using a light and magnifying lens, Dr. Byrd can closely evaluate the appearance of the optic nerve. If there is any sign of damage, and if intraocular pressure is elevated, further testing will be performed to look for additional signs of glaucoma.


A perimetry exam evaluates the patient’s complete field of vision. To perform this exam, Dr. Byrd has a patient look straight ahead while a light is passed through the peripheral field of vision. Patients are asked to indicate when they see the moving light.

By mapping out the patient’s field of vision, Dr. Byrd can assess if the field of vision has been compromised. If a patient is diagnosed with glaucoma, this test may be repeated once or twice a year so that Dr. Byrd can continue to evaluate the effect that glaucoma has on vision.


For this exam, Dr. Byrd numbs the eye and then places a handheld contact lens. The contact lens has a mirror that allows Dr. Byrd to examine the angle where the cornea meets the iris. A narrow angle may be a sign of acute glaucoma, while a wide angle may be a sign of chronic glaucoma.

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Glaucoma testing is vital to the diagnosis and treatment of this common eye disease. If you have more questions about glaucoma testing, or if you would like to schedule a comprehensive eye exam with Dr. Thomas Byrd, contact us at your earliest convenience or call (313) 383-1300.

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