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M. P. Weisberg, R. Braunstein; A Comparison of Iop Measurements by Goldmann Tonometry, Tonopen, and Palpation. Invest. Ophthalmol. Vis. Sci. 2008;49(13):708. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the reliability of intraocular pressure (IOP) readings obtained through the Tonopen XL and digital palpation as compared to the gold standard Goldmann tonometer applanation. In addition, to evaluate if a 1st year ophthalmology resident with little experience in digital palpation IOP estimation would show a learning effect and improvement in estimating IOP through digital palpation.
Fifty-six patients (a total of 111 eyes) were included in this study. All patients were over the age of 21. A single observer (a 1st year ophthalmology resident) conducted all measurements. IOP estimation by digital palpation through the eyelids was always the first measurement taken and then the IOP was measured with both Goldmann applanation and the Tonopen XL for the first 30 patients. The study was continued for 26 more patients (52 eyes) to further investigate if any learning effect could be seen as the 1st year resident became more experienced at estimating IOP through digital palpation. In the second portion of the study, only digital palpation and Goldmann tonometry was performed.
The mean IOP measured by Goldmann tonometry was 14.13mmHg (+/- 5.74) which was statistically significant from the mean IOP measured with palpation (15.56mmHg +/- 5.20) and Tonopen XL (18.81 +/- 4.71) with p<.01 by t-test. The correlation coefficient for palpation vs. Goldmann tonometry and Tonopen XL vs. Goldmann was .67 and .79, respectively, showing a higher correlation for the Tonopen XL in estimating IOP. Using palpation the examiner was correct 13.5% of the time, within 3mmHg 59.5%, within 5mmHg 81.1%, and within 10mmHg 95.5%. Using the Tonopen XL IOP estimation was correct only 1.7%, within 3mmHg 35.6%, within 5mmHg 57.6% and within 10mmHg 98.3%. When analyzed over time there was only a slight trend for improved accuracy of IOP estimation by palpation with a mean error of 3.76mmHg (+/- 3.35) over the first half of IOP measurements and 3.29mmHg (+/- 2.83) over the second half. This was not statistically significant (p=.42).
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