Comparison of Non-contact Tonometry and Goldmann Applanation Tonometry Measurements in Non-pathologic High Myopia

To compare intraocular pressure (IOP) values obtained using Goldmann applanation tonometry (IOP_GAT) and non-contact tonometry (IOP_NCT) in a non-pathologic high myopia population.

A total of 720 eyes from 720 Chinese adults with non-pathologic high myopia were enrolled in this cross-sectional study. Demographic and ocular characteristics, including axial length, refractive error, central corneal thickness (CCT), and corneal curvature (CC) were recorded. Each patient was successively treated with IOP_NCT and IOP_GAT. Univariate and multivariable linear regression analyses were conducted to detect factors associated with IOP_NCT and IOP_GAT, as well as the measurement difference between the two devices (IOP_NCT-GAT).

In this non-pathologic high myopia population, the mean IOP_NCT and IOP_GAT values were 17.60 ± 2.76 mmHg and 13.85 ± 2.43 mmHg, respectively. The IOP measurements of the two devices were significantly correlated (r = 0.681, P < 0.001), however, IOP_NCT overestimated IOP_GAT with a mean difference of 3.75 mmHg (95% confidence interval: 3.60-3.91 mmHg). In multivariate regression, IOP_NCT was significantly associated with body mass index (standardized β = 0.075, p = 0.033), systolic blood pressure (SBP) (standardized β = 0.170, p < 0.001), and CCT (standardized β = 0.526, p < 0.001). As for IOP_GAT, only SBP (standardized β = 0.162, p < 0.001), CCT (standardized β = 0.259, p < 0.001), and CC (standardized β = 0.156, p < 0.001) were significantly correlated. The mean IOP_NCT-GAT difference increased with younger age (standardized β = -0.134, p < 0.001), higher body mass index (standardized β = 0.091, p = 0.009), higher SBP (standardized β = 0.074, p = 0.027), thicker CCT (standardized β = 0.506, p < 0.001), and lower IOP_GAT (standardized β = -0.409, p < 0.001).

In the non-pathologic high myopia population, IOP_NCT overestimated IOP_GAT at 3.75 ± 2.10 mmHg. This study suggests that the difference between the values obtained by the two devices, and their respective influencing factors, should be considered in the clinical evaluation and management of highly myopic populations.