The tension of a healthy eye should be between 10 and 20 millimeters of mercury (mmHg). In the Goldman Applanation tonometry type, the cornea is flattened, and the intraocular pressure (IOP) is determined by measuring the force application and flattened area. The Goldmann tonometer measures the force required to flatten an area of 3.06-mm diameter corneal strength. IOP, expressed in mmHg is equivalent to the force in grams multiplied by an applanation of 10. The tonometer actually measures the applanation force in grams. Multiplying by 10 mmHg we obtain the IOP.
The applanation method is one of the methods we use to measure eye pressure and is often called Goldmann tonometry. Require anesthetic drops and fluorescein. When the head is balanced and still, the patients are asked to look into an instrument with a blue light and a probe will flatten the cornea. The pressure required to flatten the cornea determines the pressure of the eye. This test does not hurt because the eye is numb.