How is tonometry done?
Tonometry is generally performed upon an anesthetized ocular surface. Anesthesia is generally rendered with a single drop of topical anesthetic, such as proparicaine (Alcaine) or tetracaine (Pontocaine). The tonometer device lightly touches the surface of the eye, ever so slightly indenting the cornea. The resistance to indentation is measured by a precisely calibrated pressure sensing device, the tonometer. Several types of tonometers are available for this test, the most common being the applanation tonometer: • Goldman applanation tonometer: the “gold standard” instrument attached to the slit lamp biomicroscope used in all eye doctors’ offices. It requires a cobalt blue light source and a small droplet of fluorescein on the ocular surface. A tiny pressure sensor attached to a spring-loaded arm is gently placed against the tear film, and the doctor or technician reads the pressure through the microscope under the blue light. • Tono-Pen handheld electronic contact tonometer: This wide
