You might be surprised at how many tests eye doctors use to diagnose glaucoma. A proper diagnosis requires careful evaluation of many aspects of your eye’s health – from eye pressure to cornea thickness to the health of your optic nerve. This article describes how your eye doctor assesses your risk and all the tests needed to properly diagnose glaucoma.
Risk Factor Assessment
Your eye doctor will begin by assessing your risk level for developing glaucoma. This will help determine the frequency and extent of testing needed. Through a family history and medical questionnaire, the eye doctor is looking for the following risk factors:
- Over the age of 60
- Ethnic background such as African or black Caribbean descent, Hispanic, or Asian
- Family history of glaucoma, such as a sibling or parent with glaucoma
- History of eye conditions, injuries or surgeries
- Prolonged corticosteroid use (eye drops, pills, inhalers or creams)
- Chronic conditions that affect blood flow, such as migraines, diabetes, low blood
pressure or hypertension - Current or former smoker
If you’ve already had a comprehensive eye exam, your eye doctor will also consider these risk factors:
- Eye pressure higher than normal (above 21 mm Hg)
- Thin corneas (less than 0.5 millimeters)
Your type of eyesight is also important. People with farsightedness are at a higher risk for narrow-angle glaucoma, a more serious type that can advance quickly. While nearsightedness is associated with open-angle glaucoma, which progresses slowly without any symptoms.
Standard Glaucoma Tests
During a comprehensive eye exam, your eye doctor will always check for glaucoma, regardless of the risk level. This provides a baseline for comparison as you age. There are two tests: tonometry and ophthalmoscopy.
Tonometry
Tonometry measures the pressure within your eye. Your eye doctor will give you drops to numb your eyes. Then he/she will use a device called a tonometer, which applies a small amount of pressure with a warm puff of air.
Eye pressure is unique to each person, so it’s not always a reliable indicator for glaucoma. It’s simply another piece of information to help your eye doctor assess your eyes. The range for normal pressure is 12-22 mm Hg (“mm Hg” in millimeters of mercury, a scale for recording eye pressure). Most glaucoma cases are diagnosed with pressure over 20mm Hg. However, some people can have glaucoma at pressures between 12 -22mm Hg.
Ophthalmoscopy
This is an examination of your optic nerve. Your eye doctor will use eye drops to dilate the pupil, which makes it possible to see through your eye to examine the shape and color of the optic nerve. Then, using a small device with a light on the end, your optic nerve is magnified. Based on the results of these tests, your doctor may ask you to have more glaucoma exams.
