Glaucoma Screening
Each January we recognize National Glaucoma Awareness Month. This article focuses on screening eye examinations for the detection of glaucoma.
The purpose of glaucoma screening is to detect early stage disease so patients can be treated before there is noticeable vision loss. Screening for glaucoma is part of every comprehensive eye exam.
Glaucoma is a leading cause of irreversible blindness. Usually there are no obvious symptoms until it’s too late.
Eye Pressure Check
An eye pressure check (tonometry) is a quick and simple way to test the pressure inside your eyes. Eye pressure varies from person to person (and the time of day), but the normal range is between 12 and 22 mmHg (millimeters of mercury). An eye pressure above 20 mmHg puts you at risk for developing glaucoma.
Eye pressure is a risk factor for developing glaucoma.
Dilated Eye Exam
Using special lenses a dilated eye exam allows an eye doctor to examine your optic nerve.
If your optic nerve looks damaged or your eye pressure is elevated you will need additional tests that can determine the cause, and to assess if there is any vision loss.
Additional glaucoma tests
Gonioscopy is a procedure in which a special lens (gonioscope) is used to examine the eye’s drainage system lying internally between the cornea and the iris. The pressure inside the eye is maintained by a constant production and drainage of fluid. For the procedure, your eyes are numbed and a hand-held lens with a mirror is placed on the eye.
A gonioscopy will show if your drainage angle is too narrow for fluid to drain properly which can cause your eye pressure to rise.
Perimetry is a visual field test that produces a map of your field of vision. This test helps your doctor determine whether glaucoma has affected your field of view. You will be asked to look straight ahead, and as spots of light appear you will be asked to identify where they are.
After glaucoma is diagnosed and treatment has started, perimetry tests are done once or twice a year to monitor your vision for any changes.
Pachymetry is the measurement of the thickness of your cornea. The measurement procedure takes about a minute. A pachymetry helps your doctor make a glaucoma diagnosis because corneal thickness influences eye pressure readings. The results of your pachymetry test will help your doctor better understand your intraocular pressure and develop the best treatment plan for you.
Optical coherence tomography (OCT) is an imaging technique that provides a map of the optic nerve and measures the thickness of the nerve fiber layer of the optic nerve.
Why so Many Glaucoma Tests?
Diagnosing glaucoma can be difficult because doctors have to look at many findings and factors before making a diagnosis and beginning a treatment course. If your condition is particularly hard to diagnose or treat, you may be referred to a glaucoma specialist.