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P. Gunvant, R. D. Newcomb, E. M. Kirstein, V. E. Malinovsky, R. J. Madonna, R. E. Meetz; Correcting Goldmann Applanation Tonometer Values May Not Decrease Error in Measurement. Invest. Ophthalmol. Vis. Sci. 2008;49(13):694. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate if using the Ehlers correction factor on the intraocular pressure (IOP) measured using the Goldmann applanation tonometer (GAT) improves its agreement with the Pascal Dynamic Contour Tonometer (DCT). Further to evaluate if the agreement varied on the basis of ethnic origin.
One hundred and twenty eyes of 120 ocular healthy individuals were examined at one of the five locations. Participants underwent IOP measurement with both the DCT and the GAT. Further participants also underwent central corneal thickness measurement using an ultrasonic pachymeter. The GAT IOP measurements were corrected for effects due to corneal parameters using the Ehlers correction factor. The agreement between the DCT and the GAT& DCT and Ehlers corrected GAT IOP was analyzed. Further the correlation between the Ehlers corrected GAT IOP and the DCT IOP was analyzed. The analyses were repeated by stratifying the data by ethnic origin.
The mean IOP of the GAT, DCT and the Ehlers corrected GAT was 15.30, 16.78 and 14.68 mmHg respectively. The agreement as assessed by Bland and Altman plot for the GAT with the DCT was -4.08 to + 6.95 mmHg. The limits of agreement with the DCT widened when using the Ehlers corrected GAT IOP -4.15 to + 8.25 mmHg. The correlation coefficient for DCT and the GAT IOP was greater (r = 0.51) when compared to the correlation coefficient for DCT and the Ehlers corrected GAT IOP (r = 0.45). Of the individuals examined 88 were Caucasian and 32 were African American. The results were similar even when stratifying the data by ethnic origin.
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