Description

Schiotz tonometers are as common as mice but McLeans are not. According to Keeler et al., (Brit J. Opthalmology, 2009: 93:1101), Von Graefe’s invention of the iridectory in 1857 by for treating glaucoma created an incentive to measure ocular pressure before and after surgery. Von Graefe’s tonometer, the first, proved inaccurate as did those by Donders and others. It was not until 1884 when Koller discovered that cocaine could be used as a local anesthetic that direct pressure on the cornea was possible. Of the tonometers that followed the one developed by Schiotz C1905 proved most accurate and most popular. It was widely in use throughout a good portion of the 20th century and remains in use in some areas even today. McLean patented his tonometer in 1919 and argued that it offered notable improvements over the Schiotz, including avoiding having to change weights and use a chart,plus it was more easily read. Apparently, ophthalmologists weren’t convinced and the Schiotz continued to dominate the market. The upshot of all is this is much harder to find a McLean than a Shiotz. This one is in very nice condition and made by Meyrowitz, a top-notch optical manufacturer! Case shows evidence of use but instrument is in vg condition.