[Comparison of the accuracy of intraocular pressure measurement by Goldmann applanation tonometer and Keeler noncontact tonometer]

ABSTRACT

Glaucoma is one of the leading causes of blindness, and its major risk factor is elevated intraocular pressure. Intraocular pressure measurement is a major examination in patients with glaucoma for diagnosis and treatment follow-up. This study was carried out with the purpose of comparing the accuracy of two types of conventional tonometers for measuring intraocular pressure. In this descriptive cross-sectional study, after complete ophthalmologic examinations, intraocular pressure was measured in 142 patients [284 eyes], two times at 5-minute intervals using both Goldmann and Keeler tonometers. The obtained results were analyzed with paired t-test and Pearson's correlation test. Mean intraocular pressure in subjects that were in normal pressure range [<21mmHg] was obtained 14.03 +/- 2.35mmHg with Goldmann tonometer, and 14.28 +/- 3.05mmHg with Keeler tonometer. The mean difference of the two methods was 0.25 +/- 0.70 [p=0.015] and the correlation coefficient between two methods was calculated 0.83 [p<0.0001]. Mean intraocular pressure in high intraocular pressure range [>/= 21mmHg] was obtained 26.16 +/- 5.1mmHg with Goldmann tonometer, and 26.92 +/- 5.58mmHg with Keeler tonometer. The mean difference of the two methods was 0.76 +/- 0.44 [p=0.003], and correlation coefficient between two methods was calculated 0.97 [p<0.0001]. Based on the results of this study, both used tonometry methods had acceptable accuracy in normal intraocular pressure range, but in high-risk cases such as glaucoma, Goldmann applanation tonometer is preferred as the gold standard