The tonometer is then placed against your anesthetized cornea. In noncontact tonometry, the tonometer does not touch your eye. Instead, it blows a puff of pressurized air into your eye and records the amount of pressure. After the test You are free to leave and resume normal activities. You should avoid rubbing your eyes for at least 30 minutes after the test.
Factors affecting results - An irregularly shaped cornea requires a special tonometer.
A normal reading is about 20 mm Hg or lower. Higher readings may indicate either glaucoma or ocular hypertension. It's a quick, easy test for glaucoma. The next step - Repeat tonometry or other tests may be necessary to distinguish between glaucoma and ocular hypertension or to assess borderline cases.