Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
the measurement of pressure—usually referring specifically to intraocular pressure. All tonometric methods are based on measurement of the eyeball’s capacity for deformation.
The approximate magnitude of intraocular pressure can be estimated by digital tonometry—the examiner making a subjective judgment of the degree of firmness of the eye by pressing it with the fingers. Greater accuracy in tonometry is achieved by the use of tonometers of varying design. Impression tonometry measures the degree of indentation of the eyeball produced by the tonometer rod and translates the reading into measures of intraocular pressure. Applanation tonometry measures the extent to which the eye can be flattened; the imprint (or tonogram) produced by a cylinder’s pressure on the eye is in the shape of a small circle, whose dimensions are converted into an index of pressure.