Comparison of corneal elevation and pachymetry measurements made by two state of the art corneal tomographers with different measurement principles

Autoři: Simon Schröder aff001;  Achim Langenbucher aff001;  Jens Schrecker aff002
Působiště autorů: Institute of Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany aff001;  Department of Ophthalmology, Rudolf-Virchow-Klinikum Glauchau, Glauchau, Germany aff002
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article



To compare corneal tomography measurements (elevation and pachymetry) as made by two corneal tomographers: Pentacam AXL and CASIA 2.

Material and methods

The devices were used in a standard measuring mode. 77 normal eyes were measured five times with both devices. The data maps for anterior and posterior corneal elevation and pachymetry were exported and analyzed. Repeatability and average values were calculated for each valid data point on the exported data maps. We also calculated a corrected repeatability of the elevation data maps by removing rotation, tilt, and decentration through realignment of the elevation measurement of each eye prior to analyzing the variations in the measurement usingthe same method as for the repeatability.


Pentacam AXL offered the better (corrected) repeatability for anterior corneal elevation measurements. CASIA 2 offered better repeatability for the pachymetry measurements. The tomographers could not be used interchangeably. The central corneal thickness was measured 9 μm ± 3 μm larger when measured with Pentacam AXL compared to CASIA 2.

Klíčová slova:

Cornea – Eye diseases – Eye lens – Eyes – Intraocular lens implantation – Measurement equipment – Optical equipment – Tomography


1. Lopes BT, Ramos IC, Dawson DG, Belin MW, Ambrósio R. Detection of ectatic corneal diseases based on pentacam. Z Med Phys. 2016; 26: 136–142. doi: 10.1016/j.zemedi.2015.11.001 26777318

2. Prakash G, Agarwal A, Mazhari AI, Kumar G, Desai P, Kumar DA, et al. A new, pachymetry-based approach for diagnostic cutoffs for normal, suspect and keratoconic cornea. Eye. 2012; 26: 650–657. doi: 10.1038/eye.2011.365 22281864

3. Wilson SE, Klyce SD. Screening for Corneal Topographic Abnormalities before Refractive Surgery. Ophthalmology. 1994; 101: 147–152. doi: 10.1016/s0161-6420(94)31372-8 8302548

4. Szczotka LB, Roberts C, Herderick EE, Mahmoud A. Quantitative descriptors of corneal topography that influence soft toric contact lens fitting. Cornea. 2002; 21: 249–255. doi: 10.1097/00003226-200204000-00003 11917171

5. Norrby S. Sources of error in intraocular lens power calculation. J Cataract Refract Surg. 2008; 34: 368–376. doi: 10.1016/j.jcrs.2007.10.031 18299059

6. Preussner P-R, Hoffmann P, Wahl J. Impact of Posterior Corneal Surface on Toric Intraocular Lens (IOL) Calculation. Curr Eye Res. 2015; 40: 809–814. doi: 10.3109/02713683.2014.959708 25259550

7. Schrecker J, Langenbucher A, Seitz B, Eppig T. First results with a new intraocular lens design for the individual correction of spherical aberration. J Cataract Refract Surg. 2018; 44: 1211–1219. doi: 10.1016/j.jcrs.2018.06.055 30120004

8. Packer M, Fine IH, Hoffman RS. Aspheric intraocular lens selection based on corneal wavefront. J Refract Surg. 2009; 25: 12–20. doi: 10.3928/1081597X-20090101-03 19244948

9. Bao F, Wang J, Huang J, Yu Y, Deng M, Li L, et al. Effect of Misalignment between Successive Corneal Videokeratography Maps on the Repeatability of Topography Data. PLoS One. 2015; 10: e0139541. doi: 10.1371/journal.pone.0139541 26599442

10. Schröder S, Mäurer S, Eppig T, Seitzs B, Rubly K, Langenbucher A. comparison of corneal tomography. Repeatability, precision, misalignment, mean elevation, and mean pachymetry. Curr Eye Res. 2018; 43: 709–716. doi: 10.1080/02713683.2018.1441873 29482368

11. Synek V. Evaluation of the standard deviation from duplicate results. Accred Qual Assur. 2008; 13: 335–337. doi: 10.1007/s00769-008-0390-x

12. Noll RJ. Zernike polynomials and atmospheric turbulence. J Opt Soc Am. 1976; 66: 207.

13. Amidor I. Scattered data interpolation methods for electronic imaging systems: a survey. Journal of Electronic Imaging. 2002; 11: 157–176.

14. McAlinden C, Khadka J, Pesudovs K. A comprehensive evaluation of the precision (repeatability and reproducibility) of the Oculus Pentacam HR. Invest Ophthalmol Vis Sci. 2011; 52: 7731–7737. doi: 10.1167/iovs.10-7093 21810981

15. Piotrowiak I, Soldanska B, Burduk M, Kaluzny BJ, Kaluzny J. Measuring Corneal Thickness with SOCT, the Scheimpflug System, and Ultrasound Pachymetry. ISRN Ophthalmol. 2012; 2012: 869319. doi: 10.5402/2012/869319 24558594

16. Chen S, Huang J, Wen D, Chen W, Huang D, Wang Q. Measurement of central corneal thickness by high-resolution Scheimpflug imaging, Fourier-domain optical coherence tomography and ultrasound pachymetry. Acta Ophthalmol. 2012; 90: 449–455. doi: 10.1111/j.1755-3768.2010.01947.x 20560892

17. Neri A, Malori M, Scaroni P, Leaci R, Delfini E, Macaluso C. Corneal thickness mapping by 3D swept-source anterior segment optical coherence tomography. Acta Ophthalmol. 2012; 90: e452–7. doi: 10.1111/j.1755-3768.2012.02453.x 22682316

18. Schröder S, Chashchina E, Janunts E, Cayless A, Langenbucher A. Reproducibility and normal values of static pupil diameters. Eur J Ophthalmol. 2017: [Epub ahead of print].

19. Szalai E, Berta A, Hassan Z, Módis L. Reliability and repeatability of swept-source Fourier-domain optical coherence tomography and Scheimpflug imaging in keratoconus. J Cataract Refract Surg. 2012; 38: 485–494. doi: 10.1016/j.jcrs.2011.10.027 22261325

20. Liou HW B. Anatomically accurate, finite model eye for optical modeling. J Opt Soc Am A. 1997; 14: 1684–1695.

21. Aranha Dos Santos V, Schmetterer L, Gröschl M, Garhofer G, Schmidl D, Kucera M, et al. In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain optical coherence tomography. Opt Express. 2015; 23: 21043–21063. doi: 10.1364/OE.23.021043 26367956

22. Norrby S, Hirnschall N, Nishi Y, Findl O. Fluctuations in corneal curvature limit predictability of intraocular lens power calculations. J Cataract Refract Surg. 2013; 39: 174–179. doi: 10.1016/j.jcrs.2012.09.014 23158678

23. Kiely PM, Carney LG, Smith G. Diurnal variations of corneal topography and thickness. Am J Optom Physiol Opt. 1982; 59: 976–982. doi: 10.1097/00006324-198212000-00007 6891565

24. Zheng Y, Huang L, Zhao Y, Wang J, Zheng X, Huang W, et al. Repeatability of corneal elevation maps in keratoconus patients using the tomography matching method. Sci Rep. 2017; 7: 17457. doi: 10.1038/s41598-017-17658-7 29234085

Článek vyšel v časopise


2019 Číslo 10
Nejčtenější tento týden