Central Corneal Thickness Reproducibility among Ten Different Instruments

Luisa Pierro, Lorenzo Iuliano, Marco Gagliardi, Alessandro Ambrosi, Paolo Rama, Francesco Bandello

Research output: Contribution to journalArticle


Purpose To assess agreement between one ultrasonic (US) and nine optical instruments for the measurement of central corneal thickness (CCT), and to evaluate intra- and inter-operator reproducibility. Methods In this observational cross-sectional study, two masked operators measured CCT thickness twice in 28 healthy eyes. We used seven spectral-domain optical coherence tomography (SD-OCT) devices, one time-domain OCT, one Scheimpflug camera, and one US-based instrument. Inter- and intra-operator reproducibility was evaluated by intraclass correlation coefficient (ICC), coefficient of variation (CV), and Bland-Altman test analysis. Instrument-to-instrument reproducibility was determined by ANOVA for repeated measurements. We also tested how the devices disagreed regarding systemic bias and random error using a structural equation model. Results Mean CCT of all instruments ranged from 536 ± 42 μm to 577 ± 40 μm. An instrument-to-instrument correlation test showed high values among the 10 investigated devices (correlation coefficient range 0.852-0.995; p values <0.0001 in all cases). The highest correlation coefficient values were registered between 3D OCT-2000 Topcon - Spectral OCT/SLO Opko (0.995) and Cirrus HD-OCT Zeiss - RS-3000 Nidek (0.995), whereas the lowest were seen between SS-1000 CASIA and Spectral OCT/SLO Opko (0.852). ICC and CV showed excellent inter- and intra-operator reproducibility for all optic-based devices, except for the US-based device. Bland-Altman analysis demonstrated low mean biases between operators. Conclusions Despite highlighting good intra- and inter-operator reproducibility, we found that a scale bias between instruments might interfere with thorough CCT monitoring. We suggest that optimal monitoring is achieved with the same operator and the same device.

Original languageEnglish
Pages (from-to)1371-1379
Number of pages9
JournalOptometry and Vision Science
Issue number11
Publication statusPublished - Nov 1 2016



  • central corneal thickness
  • conversion
  • pachymetry
  • reproducibility

ASJC Scopus subject areas

  • Ophthalmology
  • Optometry

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