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September 2006

Are We There Yet? Celebrating the Centennial of the Schiøtz Tonometer

Arch Ophthalmol. 2006;124(9):1337-1338. doi:10.1001/archopht.124.9.1337

Since childhood, essentially everyone has asked or been asked “Are we there yet?” This question can elicit many reactions, including anticipation, hope, and even recognition that we have not yet reached our destination. The same responses can be applied to ophthalmology if we consider our journey in grappling with the challenge of accurately measuring one of the basic components of an ophthalmologic examination, the intraocular pressure (IOP).

The year 2005 marked the centennial of the first simple and generally reliable tonometer designed to measure the IOP, that of a Norwegian professor of ophthalmology, Hjalmar Schiøtz (1850-1927).1 For half a century his instrument became the standard for measuring IOP and it is still useful for measurements at the bedside and in the operating room. It also earned him a nomination for a Nobel Prize. Placing a Schiøtz tonometer on an eye requires topical anesthesia. Credit for discovering topical anesthesia belongs to another ophthalmologist, Carl Koller (1857-1944), for his 1884 description of the effect of cocaine. Koller would have won a Nobel Prize if the award had been created by that time. Previously, pressure-measuring devices were placed on the eyelids or awkwardly on the scleral conjunctiva without the benefit of anesthesia—a procedure undoubtedly associated with marked squeezing of the eyelids and apprehension on the part of both the patient and physician, which markedly limited the reliability of measurements. Schiøtz's invention deserves a moment of reflection since it has influenced the frequency at which IOP is measured and has emphasized the importance of IOP in managing glaucoma. Such an acknowledgment also provides us an opportunity to consider if we are any closer to Schiøtz's goal of developing a reliable and accurate instrument to measure IOP.

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