Tonometer is an instrument used for the determination of the intraocular pressure or the pressure of the fluid within the eye. Tonometry is a diagnostic test primarily used to detect glaucoma. Glaucoma is an eye disease in which the optic nerve is damaged. The buildup of the pressure of the extra fluid inside the eye damages the optic nerve, and if this is left unattended, it may first cause peripheral vision loss and could lead to permanent loss of vision. Tonometer is equipped to measure the intraocular pressure by determining the resistance of the cornea to indentation.
The normal intraocular pressure ranges from 12 to 22 mm Hg according to the Glaucoma Research Foundation, and the tonometer measures in units of “mmHg” which is the unit used to record eye pressure.

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