Whether you are experiencing symptoms of glaucoma or not (some people with glaucoma do not experience noticeable symptoms), the only way to know for certain that you have the disease is with a complete eye exam and special tests. During this comprehensive exam and the tests, our San Diego glaucoma team will be looking for signs of the disease, including elevated intraocular pressure and damage to the optic nerve. Special technology may be used to assist in confirming the diagnosis.
The first factor that should be checked when diagnosing glaucoma is intraocular pressure. This is done with a test called tonometry. Either a special probe-like device called a tonometer or a gentle puff of air is used to press on the cornea. (This is not painful.) The pressure with which the cornea pushes back is measured in millimeters of mercury. Healthy intraocular pressure is somewhere between 12 and 22 mm Hg. Anything over 20 mm Hg may indicate glaucoma.
The Optic Nerve
In addition to measuring intraocular pressure, the eye doctor will examine the optic nerve for any signs of damage. Your pupils will be dilated with special drops in order to see clearly through the eye to the optic nerve, and a small device can help magnify the doctor’s view. If the optic nerve looks unusual, the culprit could be glaucoma.
The Drainage Angle
Another structure that will be examined during a glaucoma screening is the drainage angle, or the structure between the iris and cornea that controls the outflow of fluid from the eye. This test, called gonioscopy, involves placing a special contact lens on the eye with a mirror that shows the doctor the angle. The doctor will check to see if the angle is open or closed, wide or narrow.
Field of Vision
Your complete field of vision will also be measured. This can help confirm whether glaucoma has caused any peripheral or central vision changes. You will look straight ahead and indicate when a moving light enters your side vision. The doctor essentially creates a map of your vision. This visual field is called perimetry.
Finally, the thickness of your cornea will be measured with the help of a probe called a pachymeter. This is done because your corneal thickness may be a factor in your eye pressure readings.
How Often Should I Be Screened for Glaucoma?
Early diagnosis and prompt glaucoma treatment are essential to minimizing glaucoma’s impact on vision. And the best way to catch glaucoma early is with regular, comprehensive eye examinations. If you are under the age of 40, you should have your eyes tested at least every two to four years. If you are over the age of 40, you should have an exam every one to three years. After age 55, you should have exams every one to two years, and after your 65th birthday, you should see your eye doctor every six months to a year.
If you have any risk factors for glaucoma, e.g., you are of African or Asian descent or you have a family history of the disease, you should have exams more frequently.
To book an exam with our San Diego glaucoma specialists, please call or email our practice today.