International Ophthalmology

, Volume 39, Issue 4, pp 917–923 | Cite as

Comparison of central corneal thickness measurements by ultrasound pachymetry and 2 new devices, Tonoref III and RS-3000

  • Thomas DesmondEmail author
  • Patricia Arthur
  • Kathleen Watt
Original Paper



There is currently little evidence assessing the repeatability and accuracy of central corneal thickness measurements using the devices Tonoref III and RS-3000. This study aims to compare these devices against measurements by ultrasound pachymetry.


Central corneal thicknesses were measured on 50 eyes. Measurements from two non-contact devices—Tonoref III (NIDEK CO., LTD, Gamagori, Japan) and RS-3000 (NIDEK CO., LTD, Gamagori, Japan)—were compared against ultrasound pachymetry, the gold standard. Ultrasound measurements were obtained using a ‘Pachmate’ device (DGH Technology, Inc, Exton, PA, USA). Repeatability was defined as the value that the difference between two consecutive measurements falls below 95% of the time. The within-subject standard deviation and repeatability values were calculated for Pachmate and Tonoref III by one-way ANOVA. Repeatability of RS-3000 was determined by nonparametric analysis. Agreement between Tonoref III and Pachmate was assessed by a Bland–Altman plot. Agreement between RS-3000 and Pachmate was assessed by nonparametric analysis.


The Pachmate, Tonoref III and RS-3000 had repeatability values of 16, 7.4 and 5 µm, respectively. The mean difference between Tonoref III and Pachmate was − 15 µm (95% LoAs − 31 to + 0 µm). The median value for the difference between RS-3000 and Pachmate was − 4 µm (95% of values within − 24 and + 4 µm).


The Tonoref III and RS-3000 showed good repeatability when compared to ultrasound pachymetry. However, neither instrument agreed interchangeably with CCT measurements by ultrasound pachymetry. Practitioners should determine whether the level of agreement is sufficient to meet their clinical needs.


Pachmate RS-3000 Tonoref Reproducibility of results Repeatability Agreement 


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflicts of interests.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (UNSW Sydney) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


  1. 1.
    Gordon MO, Beiser JA, Brandt JD et al (2002) The Ocular Hypertension Treatment Study: baseline factors that predict the onset of primary open-angle glaucoma. Arch Ophthalmol 120:714–720CrossRefPubMedGoogle Scholar
  2. 2.
    Chihara E (2008) Assessment of true intraocular pressure: the gap between theory and practical data. Surv Ophthalmol 53:203–218CrossRefPubMedGoogle Scholar
  3. 3.
    Randleman JB, Woodward M, Lynn MJ, Stulting RD (2008) Risk assessment for ectasia after corneal refractive surgery. Ophthalmology 115:37–50CrossRefPubMedGoogle Scholar
  4. 4.
    Auto Ref/Kerato/Tono/Pachymeter TONOREF™ III| Auto Refractometer/Auto Keratometer/Non Contact Tonometer/Pachymeter| NIDEK CO.,LTD. Accessed 30 Nov 2016
  5. 5.
    Bland JM, Altman DG (1996) Statistics Notes: measurement error. BMJ 313:744CrossRefPubMedPubMedCentralGoogle Scholar
  6. 6.
    Bland JM, Altman DG (1986) Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 327:307–310. CrossRefGoogle Scholar
  7. 7.
    Bland JM, Altman DG (1999) Measuring agreement in method comparison studies. Stat Methods Med Res 8:135–160CrossRefPubMedGoogle Scholar
  8. 8.
    Marsich MM, Bullimore MA (2000) The repeatability of corneal thickness measures. Cornea 19:792–795CrossRefPubMedGoogle Scholar
  9. 9.
    Lackner B, Schmidinger G, Pieh S et al (2005) Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound. Optom Vis Sci 82:892–899CrossRefPubMedGoogle Scholar
  10. 10.
    O’Donnell C, Maldonado-Codina C (2005) Agreement and repeatability of central thickness measurement in normal corneas using ultrasound pachymetry and the OCULUS Pentacam. Cornea 24:920–924CrossRefPubMedGoogle Scholar
  11. 11.
    De Sanctis U, Missolungi A, Mutani B et al (2007) Reproducibility and repeatability of central corneal thickness measurement in keratoconus using the rotating Scheimpflug camera and ultrasound pachymetry. Am J Ophthalmol 144:712–718CrossRefPubMedGoogle Scholar
  12. 12.
    Nam SM, Im CY, Lee HK et al (2010) Accuracy of RTVue optical coherence tomography, Pentacam, and ultrasonic pachymetry for the measurement of central corneal thickness. Ophthalmology 117:2096–2103. CrossRefPubMedGoogle Scholar
  13. 13.
    Correa-Pérez ME, López-Miguel A, Miranda-Anta S et al (2012) Precision of high definition spectral-domain optical coherence tomography for measuring central corneal thickness reliability of cirrus HD-OCT pachymetry. Invest Ophthalmol Vis Sci 53:1752–1757. CrossRefPubMedGoogle Scholar
  14. 14.
    Li H, Leung CKS, Wong L et al (2008) Comparative study of central corneal thickness measurement with slit-lamp optical coherence tomography and visante optical coherence tomography. Ophthalmology 115:796–801CrossRefPubMedGoogle Scholar
  15. 15.
    Ishibazawa A, Igarashi S, Hanada K et al (2011) Central corneal thickness measurements with Fourier-domain optical coherence tomography versus ultrasonic pachymetry and rotating Scheimpflug camera. Cornea 30:615–619CrossRefPubMedGoogle Scholar
  16. 16.
    Kim HY, Budenz DL, Lee PS et al (2008) Comparison of central corneal thickness using anterior segment optical coherence tomography vs ultrasound pachymetry. Am J Ophthalmol 145(228–232):e1. CrossRefGoogle Scholar
  17. 17.
    Nam SM, Lee HK, Kim EK, Seo KY (2006) Comparison of corneal thickness after the instillation of topical anesthetics: proparacaine versus oxybuprocaine. Cornea 25:51–54CrossRefPubMedGoogle Scholar
  18. 18.
    Simon G, Small RH, Ren Q, Parel J-M (1993) Effect of corneal hydration on goldmann applanation tonometry and corneal topography. Refract Corneal Surg Thorofare 9:110–117Google Scholar
  19. 19.
    Bechmann M, Thiel MJ, Neubauer AS et al (2001) Central corneal thickness measurement with a retinal optical coherence tomography device versus standard ultrasonic pachymetry. Cornea 20:50CrossRefPubMedGoogle Scholar
  20. 20.
    Tam ES, Rootman DS (2003) Comparison of central corneal thickness measurements by specular microscopy, ultrasound pachymetry, and ultrasound biomicroscopy. J Cataract Refract Surg 29:1179–1184. CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media B.V., part of Springer Nature 2018

Authors and Affiliations

  • Thomas Desmond
    • 1
    Email author
  • Patricia Arthur
    • 1
  • Kathleen Watt
    • 1
  1. 1.School of Optometry and Vision ScienceUniversity of New South WalesSydneyAustralia

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