Accuracy and reliability of measurements obtained with a noncontact tono-pachymeter for clinical use in mass screening

Jinho Lee,Hyuk Jin Choi

doi:10.1038/s41598-021-88364-8

Abstract

We evaluated the reliability and accuracy of the noncontact CT-1P tonopachymeter (Topcon, Japan) in terms of intraocular pressure (IOP) and central corneal thickness (CCT). One hundred sixty-three healthy participants and 33 patients with open angle glaucoma were enrolled. IOPs were measured by CT-1P (T-IOP) and Goldmann applanation tonometer (G-IOP), and CCTs were measured by the CT-1P (T-CCT) and an ultrasound pachymeter (US-CCT). Both CCT instrument-adjusted (T-IOP-C) and unadjusted T-IOPs (T-IOP-NC) were included. Pearson correlation coefficients and biases assessed with Bland–Altman analysis with 95% confidence interval (CI) were calculated for reliability evaluation. Intrasession repeatability was excellent for both T-IOP (intraclass correlation coefficient [ICC] 0.91) and T-CCT (ICC 0.98). Intersession reproducibility was also excellent for T-CCT (ICC 0.94). T-IOP-NC and T-IOP-C both showed significant correlations with G-IOP (r = 0.801, P < 0.001 and r = 0.658, P < 0.001, respectively). T-CCT was also strongly correlated with US-CCT (r = 0.958; P < 0.001). T-IOP-NC and T-IOP-C both showed a positive bias (1.37 mmHg, 95% CI [1.14, 1.61] and 2.77 mmHg, 95% CI [2.49, 3.05], respectively). T-CCT showed a negative bias of − 17.3 µm (95% CI [−18.8, − 15.8]). With cautious interpretation, the CT-1P may offer good feasibility for IOP and CCT measurement in screening centers.

Highlights

We evaluated the reliability and accuracy of the noncontact CT-1P tonopachymeter (Topcon, Japan) in terms of intraocular pressure (IOP) and central corneal thickness (CCT)
163 subjects were healthy controls enrolled from a glaucoma screening program, and 33 glaucoma patients were recruited from the Glaucoma Outpatient Clinic at the Seoul National University Hospital (SNUH) Healthcare System Gangnam Center (HSGC)
There were no significant differences in the IOP measured by the CT-1P without (T-IOP-NC) or with correction for CCT (T-IOP-C), the IOP measured by Goldmann applanation tonometry (GAT) (G-IOP), the CCT measured by the CT- 1P (T-CCT), or the CCT measured by US pachymetry (US-CCT) between the two groups

Summary

Introduction

We evaluated the reliability and accuracy of the noncontact CT-1P tonopachymeter (Topcon, Japan) in terms of intraocular pressure (IOP) and central corneal thickness (CCT). Goldmann applanation tonometry (GAT) has been considered the gold standard method of IOP measurement[1,2,3] It has some unignorable drawbacks compared with noncontact tonometers (NCTs). Among various instruments for CCT measurement, ultrasound (US) pachymetry has been widely considered the gold standard method by virtue of its easy and fast acquisition and good repeatability[10,11]. It has some disadvantages: (i) direct placement of the probe on the cornea, which is susceptible to infection and corneal epithelial damage, (ii) the necessity for topical anesthesia, and (iii) dependence on examiner experience for reliable m easurements[12]. To the best of our knowledge, there are no reports investigating the repeatability and reliability of this tono-pachymeter

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