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Eye Tests and Exams

Non-Contact Tonometry

This eye test is used to help diagnose glaucoma. An instrument known as a tonometer measures the pressure in the eye. The "air puff" tonometer measures the eye pressure indirectly by the eye's resistance to a puff of air.

Applanation instruments can also be used to measure pressure. They are the most accurate, but they require local anesthetic.


An ultrasound eye test uses sound waves to provide a picture of the eye's internal structure. It is useful in evaluating ocular tumors, as well as the retina when it is being obscured by cataracts or a hemorrhage. Measuring the length of the eye by ultrasound or other means is part of preoperative evaluation for cataract surgery and determination of the optimal cataract implant power.


Visual Acuity Testing

This is a test of visual acuity, your ability to see sharply and clearly at near and far distances. For children who cannot yet read, there is the Random E's Visual Acuity Test. The child is asked to identify the direction that the letter "E" opens to by holding out three or four fingers to mimic the letter. You can practice this at home with your child before the test. This eye test is safe, there are no risks involved, and it works just as well as most other eye tests.

Visual Field Test

This is an eye test used to measure peripheral (side) vision. When taking this test, you will be asked to stare at on object in the center of your line of vision (either the doctor's eyes or a computer screen). As you look at the target, you will be asked to note when you see an object moving into your peripheral vision. This test is done to measure loss of vision from conditions such as stroke or glaucoma.


WebMD Medical Reference

Reviewed by Alan Kozarsky, MD on August 01, 2014

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