There are different methods for determining the intraocular pressure:
When measuring the intraocular pressure with the non-contact tonometer, the cornea is not touched. The cornea is flattened by a short, gentle air-puff. The resulting deformation of the cornea is measured by the device and a corresponding intraocular pressure is determined.
The most accurate method is applanation tonometry. It is completely painless because the surface of the eye is locally anesthetized with eye drops before the examination. The eye pressure is determined at the slit lamp by lightly touching the cornea with a measuring head.
If the pressure values are abnormal, a thorough investigation is carried out with regard to glaucoma, one of the most common causes of blindness in old age.
Therefore, from 40 years on visit your ophthalmologist once a year.