Video by Scott Pasichow; Text by Joseph Moran
A 40-year-old patient with a history of migraine and glaucoma presented to the ED with concern of acute frontal headache with visual changes. The patient was well-appearing without acutely concerning neurologic or ophthalmologic findings on physical exam. As part of his workup, an intraocular pressure was desired to rule out increased IOP/glaucoma. An electronic tonometer was unavailable for use. Instead, the Schiotz tonometer was utilized.
A Schiotz tonometer is an analog, weight-based tool to assess intraocular pressure. It uses a weight on a flat transducer which is opposed by the intraocular pressure. The IOP is transferred through the weighted tonometer arm and gives a reading on a needle, which is then used on a conversion table to calculate IOP.
Tonometer, 7.5, 10, and 15 gram weights, conversion table.
Steps of use:
Apply one of the 3 included weights to the Schiotz tonometer as demonstrated in the video. Start at 5.5 and change to heavier as needed if reading is too high (e.g., off the charts)
Have the patient look straight ahead while lying supine
Apply the flat round bottom of the tonometer to the middle of the cornea (e.g., mid-pupil)
Write down (or remember) the reading on the needle
Use conversion table based on weight used and needle reading to calculate IOP
Clean with alcohol swab
The patient's IOP was within normal limits, symptoms improved with symptomatic care, and the patient was discharged home with outpatient follow up and return precautions.
Faculty Reviewer: Dr. Whit Fisher