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Cho, Jun, and Choi: Reproducibility of Ocular Response Analyzer and Comparison with Goldmann Applanation Tonometer and Non-Contact Tonometer
Original Article
Journal of the Korean Ophthalmological Society

Journal of the Korean Ophthalmological Society 2012; 53(9): 1311-1317.

Published online: 17 September 2012

DOI: https://doi.org/10.3341/jkos.2012.53.9.1311

Reproducibility of Ocular Response Analyzer and Comparison with Goldmann Applanation Tonometer and Non-Contact Tonometer

Ga Eun Cho, MD, Roo Min Jun, MD, PhD, Kyu-Ryong Choi, MD, PhD

The Institute of Ophthalmology and Optometry, Department of Ophthalmology, Ewha Womans University School of Medicine, Seoul, Korea.

Address reprint requests to Kyu-Ryong Choi, MD, PhD. Department of Ophthalmology, Ewha Womans University Medical Center, #1071 Anyangcheon-ro, Yangcheon-gu, Seoul 158-710, Korea. Tel: 82-2-2650-5154, Fax: 82-2-2654-4334, ckrey02@ewha.ac.kr

Received 15 November 2011       Accepted 14 July 2012

Copyright © 2012 The Korean Ophthalmological Society

Abstract

Purpose

To evaluate the inter- and intra-observer variability of ocular response analyzer (ORA) measurements, and to evaluate the relationships among the intraocular pressures (IOPs) obtained by ORA, Goldmann applanation tonometer (GAT) and non-contact tonometer (NCT).

Methods

The present study included 45 normal eyes from 45 volunteers. Three masked observers performed ORA measurements. NCT and GAT measurements were performed by one independent observer. The reproducibility of ORA was assessed by ANOVA-based intraclass correlation coefficient (ICC) and coefficient of variation (CV). Comparison among the tonometers was performed using the Bland-Altman plot and paired t-test.

Results

The ICC for inter-observer reproducibility of ORA parameters was 0.90 to 0.97. The corresponding CV values were 13.2% to 19.1%. The intra-observer ICC values for IOP cc were 0.78 to 0.88. CV was 11.2% to 16.8%. For CRF, ICC values were 0.80 to 0.84 with CV values as 11.6% to 15.9%. For CH, ICC values were 0.74 to 0.82 and CV values were 13.0% to 15.9%. The difference in mean IOP values between IOP cc and IOP g was statistically significant (p = 0.04). However, no difference was found among other tonometers, and only IOP cc did not result in significant correlation with central corneal thickness (CCT) (p = 0.38).

Conclusions

The intra- and inter-observer reproducibility was substantial for IOP cc, IOP g, CH and CRF, for all observers. Additionally, IOP measured with ORA did not result in significant differences from GAT and NCT.

Keywords: Central corneal thickness, Intraocular pressure, ORA, Repeatability, Tonometer

Figures and Tables

Figure 1
Measurement of corneal hysteresis. During an ORA measurement, air pulse causes the cornea to move inward. After cessation of air pulse, outward movement occurs and this makes two signal peaks. The difference between these inward and outward applanation pressure is called corneal hysteresis (CH).
jkos-53-1311-g001
Figure 2
Bland-Altman plots of agreement between IOP g and GAT-IOP, and IOP cc and GAT-IOP. The difference between the measurements is plotted against the average of the measurements. Dotted lines represent 95% limit of agreement. The differences in mean IOP values between IOP g and GAT-IOP (0.31 mm Hg), between IOP cc and GAT-IOP (-0.07 mm Hg) were not statistically significant.
jkos-53-1311-g002
Figure 3
Statistical correlations between IOP g, IOP cc and CCT. CCT was significantly associated with IOP g (r = 0.45, p = 0.002), but not with IOP cc (r = 0.14, p = 0.38). CCT was also correlated with GAT-IOP (r = 0.50, p < 0.001), NCT-IOP (r = 0.57, p < 0.001), CH (r = 0.44, p = 0.002) and CRF (r = 0.46, p = 0.002).
jkos-53-1311-g003
Table 1
Baseline characteristics of the study population
jkos-53-1311-i001

CCT = central corneal thickness.

Table 2
Inter-observer reproducibility of IOP cc, CH, CRF and IOP g
jkos-53-1311-i002

The inter-observer reproducibility of ORA measurements was almost perfect for all investigated parameters.

ICC = intraclass correlate on coefficient; CV = coefficient of variation.

Table 3
Intra-observer reproducibility
jkos-53-1311-i003

Intra-observer short-term reproducibility was substantial for IOP cc and CH, and almost perfect for IOP g and CRF.

ICC = intraclass correlation coefficient; CV = coefficient of variation.

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