Tonometry is one of the examinations to determine whether you are at risk of glaucoma.
Inside of the eye, liquid called aqueous humor flows to provide nutrition.
This pressure is called intraocular pressure.
If the degree of intraocular pressure rises, the optic nerve will be damaged.
The damage of the optic nerve will make one's vision narrower, and once it is damaged it will not be back in order as before.
The normal degree of intraocular pressure is said to be 10-21mmHg. To measure the average value, you will feel air puffed by the Noncontact Tonometer.