Intraoperator Repeatability and Interoperator Reproducibility in the Ultrasonic Pachymetry Measurements of Central Corneal Thickness
Weerawat Kiddee MD*, Orasa Horattanareung MD*
Affiliation : * Department of Ophthalmology, Faculty of Medicine, Prince of Songkla University, Songkla, Thailand
Objective : To assess the repeatability and reproducibility of central corneal thickness (CCT) measurement by
the commercial available ultrasonic pachymeter in Songklanagarind Hospital.
Material and Method: Seventy eyes underwent two sessions of CCT measurements, each session consisting of
two CCT measurements, performed by two different operators. The mean and standard deviation of the mean
differences were calculated. The interoperator repeatability and interoperator reproducibility were calculated
by means of intraclass correlation coefficient (ICC). Agreement was analyzed by means of Bland-Altman plots.
Results : The mean CCT for 70 eyes was 537.61 + 26.66 mm. The intraoperator repeatability study of the first
operator, the mean difference between the repeated measurements was 0.49 mm. The ICC was 0.985 (p <
0.001). For the second operator, the mean difference between the repeated measurements was 0.57 mm. The
ICC was 0.935 (p < 0.001). A Bland-Altman plot of both operators showed narrow limits of agreement with
respect to CCT for both operators. The mean measurement difference between operator was 0.96 mm and the
ICC for reproducibility study was 0.979 (p < 0.01). The Bland-Altman plot showed narrow limits of agreement
with respect to CCT.
Conclusion : The measurement of CCT using the ultrasonic pachymeter is highly repeatable and reproducible.
Keywords : Anthropometry, Cornea, Reproducibility of results, Ultrasonography
