Abstract
Microprocessors have enabled new techniques to be applied to the design of tonometers. Three new microprocessor controlled tonometers, one operating to the principle of Mackay-Marg (Tono-Pen) and two non-contact airstream tonometers (Pulsair and CT-10) have been examined using as a reference Goldmann and the Hand Held Applanation Tonometers (Draeger-HAT) which used the Goldmann applanation principle. The non-contact tonometers produce a conically formed air- stream with top speeds of 90 m/s (CT-10) and 70 m/s (Pulsair) which at the moment of pressure measurement applanates the cornea exactly with a diameter of 4 mm. The readings of the microprocessor controlled tonometers correlate well with the readings of HAT (Tono-Pen r=0.8414 and s=3.783, CT-10 r=0.8606 and s=4.5477, Pulsair r=0.8968 and s=3.2641, where r is the correlation coefficient and s is the standard deviation in mmHg). Repeated measurements with one tonometer give the following standard deviations (HAT 1.6617, Tono-Pen 3.4969, CT-10 2.9179, Pulsair 2.9434). Although the three new instruments are able to measure the intraocular pressure in a wide range they do not work with the same precision as the classical applanation tonometer.
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Draeger, J., Rumberger, E., Dauper, J. et al. Microprocessor controlled tonometry. Eye 3, 738–742 (1989). https://doi.org/10.1038/eye.1989.114
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DOI: https://doi.org/10.1038/eye.1989.114
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