An instrument which measures pressure inside the eye.
A small instrument for measuring the pressure inside the eye. There are two commonly used types, both applied to the cornea after a drop of local anesthetic has been put in the eye. The indentation (Schiotz) tonometer uses a small plunger that indents the cornea by an amount corresponding to the softness (determined by pressure) of the eye. The applanation tonometer measures the pressure required to flatten a constant area of the cornea. A high pressure is required when the pressure inside the eye is increased, and vice versa.