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U. Hammer, H. Specht, N. Stuebiger; Non-Contact- and Applanation-Tonometry in Comparison to the New Impression-Tonometer, the TonoScan . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2208.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Glaucoma is the leading cause of irreversible blindness worldwide. Therefore measurement of intraocular pressure (IOP) plays an important role in the detection and management of glaucomatous conditions. Methods: The main objective of our study was to find out how well two tonometers (noncontact tonometer CT–20D and TonoScan TGDc–01) compare with the Goldmann tonometer. A total of 59 healthy volunteers (118 eyes) were measured. The mean age was 33.2 years. An average of three intraocular pressure measurements, generated by the CT–20D and an average of nine intraocular pressure measurements generated by the TonoScan were compared with a single reading from Goldmann applanation tonometer. Both eyes were measured using the noncontact tonometer first, TonoScan second and the Goldmann applanation tonometer third. Results: The mean IOP and the standard deviation of the TonoScan measurements was 16.9 mmHg ± 4.9 in the right eyes, 15.9 mmHg ± 4.9 in the left eyes. The noncontact tonometer measured an average IOP of 15.8 mmHg ± 3.2 in the right and 15.3 ± 3.2 in the left eyes. The mean IOP and the standard deviation of the Goldmann applanation tonometer was 15.1 ± 2.9 in the right eyes, 15.2 ± 2.8 in the left eyes. The difference in the mean IOP between noncontact tonometry and Goldmann applanation tonometer was not significant (p>0,05), but the difference in the mean IOP between the TonoScan and Goldmann applanation tonometry was highly significant (p≤0,01). Interestingly, the difference in the mean IOP between noncontact tonometer and TonoScan was statistically not significant (p>0,05). We also calculated the correlation of the results. Between applanation tonometer and noncontact tonometer the correlation between the results is strong in the right eyes (r=0.697) and in the left eyes (r=0.727), whereas there is a low correlation between the results of the applanation tonometer and the TonoScan with r = 0.389 in the right and r=0,331 in the left eyes. Over and above that the patient`s subjective comfort of IOP measuring was also evaluated. Conclusions: The measurement of IOP with the TonoScan is not comparable to the Goldmann applanation tonometry, whereas the measurement of IOP with the noncontact tonometer is comparable to the Goldmann applanation tonometer.
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