Comparison of Corvis ST Tonometer to Other Tonometers and Clinical Usefulness of Corvis ST Tonometer

Jung Woo Han; Seung Joo Ha

doi:10.7469/JKOS.2015.56.03.404

Journal List > J Korean Ophthalmol Soc > v.56(3) > 1010220

Go to TopGo to Top Go to BottomGo to Bottom

TOOLS

Han and Ha: Comparison of Corvis ST Tonometer to Other Tonometers and Clinical Usefulness of Corvis ST Tonometer

Original Article

J Korean Ophthalmol Soc 2015;56(3):404-412.

Published online: 7 September 2015

DOI: https://doi.org/10.7469/JKOS.2015.56.03.404

Comparison of Corvis ST Tonometer to Other Tonometers and Clinical Usefulness of Corvis ST Tonometer

Jung Woo Han, MD, Seung Joo Ha, MD, PhD

Department of Ophthalmology, Soonchunhyang University Hospital, Soonchunhyang University College of Medicine, Seoul, Korea

￭ Address reprint requests to Seung Joo Ha, MD, PhD Department of Ophthalmology, Soonchunhyang University Hospital, #59 Daesagwan-ro, Yongsan-gu, Seoul 140-743, Korea Tel: 82-2-709-9354, Fax: 82-2-795-3687 E-mail: sjha@schmc.ac.kr

Received 14 August 201429 October 2014 Accepted 1 March 2015

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

초록

Purpose:

To compare the accuracy and agreement of intraocular pressure (IOP) and central corneal thickness (CCT) measurements with noncontact tonometer Corvis Scheimpflug Technology (Corvis ST) versus noncontact tonometer (NCT), Goldmann applanation tonometer (GAT), rebound tonometer (RBT), and ultrasound-based corneal pachymetry (US-CCT). The secondary objective was to evaluate the corneal biomechanical values using Corvis ST tonometer in patients with glaucoma.

Methods:

Thirty-one healthy participants and 47 patients with primary open angle glaucoma and normal tension glaucoma were enrolled in this study. One eye was selected randomly. In each participant, GAT, NCT, RBT, US-CCT and measurements with Corvis ST (Corvis-IOP and Corvis-CCT) were obtained. IOP and CCT measurements of each device were compared. Device agreement was calculated by Bland-Altman analysis. Additionally, corneal highest concavity parameters were compared between healthy subjects and glaucoma patients.

Results:

Mean IOPs in all examined eyes were 13.28 ± 2.32 mm Hg for CST, 14.71 ± 2.95 mm Hg for GAT, 14.44 ± 3.10 mm Hg for NCT, and 13.23 ± 2.89 mm Hg for RBT. There was no statistical difference in IOP measurements among tonometers. Correlation analysis showed a high correlation between each pair of tonometers (all p < 0.0001). Bland-Altman plots of all devices revealed good agreement of the IOP and CCT measurements. In glaucoma patients, highest concavity time and peak distance of highest concavity parameters were statistically lower than in normal subjects (16.93 ± 0.66 ms vs. 16.48 ± 0.84 ms p = 0.020, 4.23 ± 1.34 mm vs. 3.41 ± 1.27 mm p = 0.017, respectively).

Conclusions:

The CST, a newly-developed tonometer with features of visualization and measurement of the corneal deformation response to an air impulse, can be considered a reliable alternative method for measuring IOP and CCT in healthy subjects and glaucoma patients. Highest concavity parameters could be another important indicator identifying corneal viscosity or elasticity in patients with glaucoma.

Keywords: Corneal biomechanics values, Corvis scheimpflug technology tonometer, Glaucoma, Intraocular pressure

References

1. Comparison of glaucomatous progression between untreated patients with normal-tension glaucoma and patients with therapeuti-cally reduced intraocular pressures. Collaborative Normal-Tension Glaucoma Study Group. Am J Ophthalmol. 1998; 126:487–97.

2. Leske MC, Heijl A, Hyman L, et al. Predictors of long-term progression in the early manifest glaucoma trial. Ophthalmology. 2007; 114:1965–72.

3. Chihara E. Assessment of true intraocular pressure: the gap between theory and practical data. Surv Ophthalmol. 2008; 53:203–18.

4. Doughty MJ, Zaman ML. Human corneal thickness and its impact on intraocular pressure measures: a review and meta-analysis approach. Surv Ophthalmol. 2000; 44:367–408.

5. Liu J, Roberts CJ. Influence of corneal biomechanical properties on intraocular pressure measurement: quantitative analysis. J Cataract Refract Surg. 2005; 31:146–55.

6. Cook JA, Botello AP, Elders A, et al. Systematic review of the agreement of tonometers with Goldmann applanation tonometry. Ophthalmology. 2012; 119:1552–7.

7. Kotecha A, White ET, Shewry JM, Garway-Heath DF. The relative effects of corneal thickness and age on Goldmann applanation tonometry and dynamic contour tonometry. Br J Ophthalmol. 2005; 89:1572–5.

8. Broman AT, Congdon NG, Bandeen-Roche K, Quigley HA. Influence of corneal structure, corneal responsiveness, and other ocular parameters on tonometric measurement of intraocular pressure. J Glaucoma. 2007; 16:581–8.

9. Kwon TH, Ghaboussi J, Pecknold DA, Hashash Y. Role of corneal biomechanical properties in applanation tonometry measurements. J Refract Surg. 2010; 26:512–9.

10. Sullivan-Mee M, Billingsley SC, Patel AD, et al. Ocular Response Analyzer in subjects with and without glaucoma. Optom Vis Sci. 2008; 85:463–70.

11. Huseynova T, Waring GO 4th, Roberts C, et al. Corneal biomechanics as a function of intraocular pressure and pachymetry by dynamic infrared signal and Scheimpflug imaging analysis in normal eyes. Am J Ophthalmol. 2014; 157:885–93.

12. Luce DA. Determining in vivo biomechanical properties of the cornea with an ocular response analyzer. J Cataract Refract Surg. 2005; 31:156–62.

13. Hong J, Xu J, Wei A, et al. A new tonometer--the Corvis ST tonometer: clinical comparison with noncontact and Goldmann applanation tonometers. Invest Ophthalmol Vis Sci. 2013; 54:659–65.

14. Chang DH, Stulting RD. Change in intraocular pressure measurements after LASIK the effect of the refractive correction and the la-mellar flap. Ophthalmology. 2005; 112:1009–16.

15. Kotecha A. What biomechanical properties of the cornea are rele-vant for the clinician? Surv Ophthalmol. 2007; 52(Suppl 2):S109–14.

16. Morita T, Shoji N, Kamiya K, et al. Corneal biomechanical properties in normal-tension glaucoma. Acta Ophthalmol. 2012; 90:e48–53.

17. Terai N, Raiskup F, Haustein M, et al. Identification of biomechanical properties of the cornea: the ocular response analyzer. Curr Eye Res. 2012; 37:553–62.

18. Yu AY, Duan SF, Zhao YE, et al. Correlation between corneal biomechanical properties, applanation tonometry and direct intra-cameral tonometry. Br J Ophthalmol. 2012; 96:640–4.

19. Smedowski A, Weglarz B, Tarnawska D, et al. Comparison of three intraocular pressure measurement methods including biomechanical properties of the cornea. Invest Ophthalmol Vis Sci. 2014; 55:666–73.

20. Poostchi A, Mitchell R, Nicholas S, et al. The iCare rebound tonometer: comparisons with Goldmann tonometry, and influence of central corneal thickness. Clin Experiment Ophthalmol. 2009; 37:687–91.

21. Martinez-de-la-Casa JM, Garcia-Feijoo J, Castillo A, Garcia-Sanchez J. Reproducibility and clinical evaluation of rebound tonometry. Invest Ophthalmol Vis Sci. 2005; 46:4578–80.

22. Jablonski KS, Rosentreter A, Gaki S, et al. Clinical use of a new po-sition-independent rebound tonometer. J Glaucoma. 2013; 22:763–7.

23. Bhartiya S, Bali SJ, Sharma R, et al. Comparative evaluation of TonoPen AVIA, Goldmann applanation tonometry and non-contact tonometry. Int Ophthalmol. 2011; 31:297–302.

Figure 1.

Intraocular pressure measurement by CST. A high speed Scheimpflug camera was equipped to record the movement of cornea. The output also includes central corneal thickness and corneal biomechanical properties (applanation time, applanation length, applanation velocity, and parameters of highest concavity). CST = Corvis scheimpflug technology; IOP = intraocular pressure.

Figure 2.

Analysis of variance between mean intraocular pressure values measured by different tonometers. There was no statistically significant difference in IOP measurement among the tonometers by ANOVA (CST vs GAT, p = 0.265 CST vs NCT, p = 0.057 CST vs RBT, p = 0.744). IOP = intraocular pressure; CST = Corvis scheimpflug technology; GAT = Goldmann applanation tonometer; NCT = noncontact tonometer; RBT = rebound tonometer.

Figure 3.

Bland-Altman plots between different tonometers. The solid line indicates mean difference of both tonometers. The dotted lines are 95% of limits of agreement. CST = Corvis scheimpflug technology; GAT = Goldmann applanation tonometer; NCT = noncontact tonometer; RBT = rebound tonometer.

Figure 4.

Correlation of CST, GAT, NCT and RBT. Significant positive correlations were noted between CST and GAT (R = 0.670, p < 0.001), between CST and NCT (R = 0.746, p < 0.001) and between CST and RBT (R = 0.679, p < 0.001) by Spearman correlation. CST = Corvis scheimpflug technology; GAT = Goldmann applanation tonometer; NCT = noncontact tonometer; RBT = rebound tonometer.

Figure 5.

Bland-Altman plots between US-CCT and Corvis-CCT. The solid line indicates mean difference of both tonometers. The dotted lines are 95% of limits of agreement. US = ultrasound; CCT = central corneal thickness.

Table 1.

Demographic characteristics of study subjects

Demographics	Values
Total (n)	78 patients
	(37 females and 41 males)
Healthy subjects	31
Glaucoma patients	47 (POAG:20, NTG:27)
Age (years)
Healthy subjects	51.6 ± 17.1
Glaucoma patients	59.0 ± 5.0
p-value^*	0.057
Axial length (mm)
Healthy subjects	24.36 ± 1.71
Glaucoma patients	24.75 ± 1.49
p-value^*	0.312
Central corneal thickness (μ m)
Healthy subjects	544.6 ± 34.9
Glaucoma patients	533.5 ± 39.1
p-value^*	0.216
Corneal curvature (mm)
Healthy subjects	7.68 ± 0.66
Glaucoma patients	7.82 ± 0.61
p-value^*	0.387
Corneal astigmatism (diopter)
Healthy subjects	1.13 ± 0.70
Glaucoma patients	0.96 ± 0.58
p-value^*	0.245

Values are presented as mean ± SD unless otherwise indicated.

POAG = primary open angle glaucoma; NTG = normal tension glaucoma.

^* By student’s t-test.

Table 2.

Mean intraocular pressure values measured by different tonometers in normal subjects and glaucoma patients

Tonometers	Values
Corvis ST tonometer (mm Hg)
Healthy subjects	13.37 ± 2.53
Glaucoma patients	12.77 ± 2.37
Total	13.28 ± 2.32
p-value^*	0.298
Goldmann applanation tonometer (mm Hg)
Healthy subjects	14.60 ± 2.98
Glaucoma patients	14.86 ± 2.94
Total	14.71 ± 2.95
p-value^*	0.700
Noncontact tonometer (mm Hg)
Healthy subjects	14.48 ± 3.50
Glaucoma patients	14.20 ± 2.88
Total	14.44 ± 3.10
p-value^*	0.710
Rebound tonometer (mm Hg)
Healthy subjects	13.01 ± 3.20
Glaucoma patients	13.56 ± 2.34
Total	13.23 ± 2.89
p-value^*	0.420

Values are presented as mean ± SD.

Corvis ST = Corvis scheimpflug technology.

^* By student’s t-test.

Table 3.

Correlation between different tonometers

		CST	GAT	NCT	RBT
Spearman correlation	CST	1	0.670^*	0.746^*	0.679^*
	GAT	0.670	1	0.656	0.645
	NCT	0.746	0.656	1	0.684
	RBT	0.679	0.645	0.684	1

Values present the correlation of intraocular pressure (IOP) gained from all subjects (healthy subjects and glaucoma patients).

CST = Corvis scheimpflug technology; GAT = Goldmann applanation tonometer; NCT = noncontact tonometer; RBT = rebound tonometer.

^* p-value < 0.001.

Table 4.

Mean CCT obtained with ultrasound pachymetry and Corvis ST tonometry of normal subjects and glaucoma patients

	Mean US-CCT	Mean Corvis-CCT	Correlation (Pearson’s coefficient)
Glaucoma patients	532.40 ± 38.18	534.87 ± 40.31	0.965
			p < 0.0001
Normal subjects	542.74 ± 35.93	547.29 ± 38.06	0.933
			p < 0.0001

Values are presented as mean ± SD.

US = ultrasound; CCT = central corneal thickness; Corvis ST = Corvis scheimpflug technology.

Table 5.

Mean value parameters of highest concavity from Corvis ST for each subgroup of corneal compensated intraocular pressure groups

	Highest concavity
	Time	Peak distance	Radius	Deformation amplitude
Glaucoma patients	16.48 ± 0.84	3.41 ± 1.27	6.85 ± 0.78	1.11 ± 0.16
Normal subjects	16.93 ± 0.66	4.23 ± 1.34	7.19 ± 0.78	1.18 ± 0.13
p-value^*	0.020^*	0.017^*	0.088	0.051

Values are presented as mean ± SD.

Corvis ST = Corvis scheimpflug technology.

^* By student’s t-test.

TOOLS

Similar articles