(ophthalmotonometer) n. 1. a small instrument for measuring the pressure inside the eye. There are several types. The applanation tonometer measures the force required to flatten a known area of the cornea after a drop of local anaesthetic has made the cornea numb. A greater force is required when the pressure inside the eye is increased, and vice versa. The Goldmann applanation tonometer flattens a corneal area of 3 mm2. See also pneumotonometer. 2. an instrument for measuring pressure in some other part of the body.
—tonometry n.
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