Comparative Assessment of Intraocular Pressure Measurement Between Non-Contact tonometry and Goldmann Applanation Tonometry among Glaucoma Patients in Angthong Hospital

Abstract

          Objective: To compare the intraocular pressure (IOP) values acquired from non-contact tonometry and a Goldmann applanation tonometry in glaucoma patients.

          Design: A prospective, cross-sectional study

          Methods: This study involved 400 eyes from 200 glaucoma patients who attended the glaucoma outpatient clinic, Angthong hospital during January 4th, 2021 to June 30th, 2021. IOP measurements were obtained using non-contact tonometry (NCT) and Goldmann applanation tonometry (GAT). The differences in intraocular pressure (IOP) readings between the two techniques were evaluated using paired t-test and calculating the Pearson correlation coefficient. A Bland-Altman analysis was used to determine the limit of agreement between the two techniques.

          Results: The mean intraocular pressure as measured by NCT was 17.29 ± 4.21 mmHg, compare the mean intraocular pressure as measured by GAT was 16.50 ± 3.74 mmHg. The mean differences intraocular pressure readings between the two techniques were 0.79 ± 1.09 mmHg. There was a strong correlation between NCT and GAT finding in the right eye (r = 0.807, n = 200, P < 0.001) and in the left eye (r = 0.857, n = 200, P < 0.001). Bland-Altman plots, limit of agreement range from -3.88 to 5.81 mmHg in the right eye (mean = 0.95) and limit of agreement range from -3.67 to 4.92 mmHg in the left eye (mean = 0.62).

          Conclusions: In this study found that NCT readings were significant difference and higher IOP readings of the GAT; but within the clinically acceptable inter device measure for IOP. The NCT and GAT measurements correlated positively. NCT can be used as a screening tool for IOP testing in the high volume clinic. However, NCT cannot replace the existing gold standard method for IOP measurement, the GAT.