Intraocular Pressure (IOP) Measurements

IOPIntraocular Pressure (IOP) measurement uses a tonometer to measure the pressure (mmHg) within the eye. Alteration in IOP can represent, for example, a desirable effect of an anti-glaucoma drug or a toxic effect.

  • Applanation tonometry:   A topical anesthetic is applied to the surface of the eye and force is applied to flatten (applanate) an area of the cornea.  Intraocular pressure is measured when the probe makes contact with the cornea.  Instruments include:  Tono-Pen, pneumotonometer, Goldmann tonometer.
  • Rebound tonometry:  A simple magnetized probe is bounced against the cornea and then back into the device, creating an induction current that is used to calculate intraocular pressure. Advantages include:  topical anesthesia is not required and the instrument's calibration can be varied by species.