Precision of corneal thickness measurements obtained using the scheimpflug-placido imaging and agreement with ultrasound pachymetry

Purpose. to assess the reliability and comparability of measuring central corneal thickness (cct) and thinnest corneal thickness (tct) using a new scheimpflug-placido analyzer (tms-5,japan) and ultrasound (us) pachymetry. methods. seventy-six healthy subjects were prospectively measured 3 times by 1 operator using the tms-5,3 additional consecutive scans were performed by a second operator,and ultrasound (us) pachymetry measurements were taken. the test-retest repeatability (trt),coefficient of variation (cov),and intraclass correlation coefficient (icc) were calculated to evaluate intraoperator repeatability and interoperator reproducibility. agreement among the devices was assessed using bland-altman plots and 95% limits of agreement (loa). results. the intraoperators trt and cov were <19 m and 2.0%,respectively. the interoperators trt and cov were <12 m and 1.0%,respectively,and icc was >0.90. the mean cct and tct measurements using the tms-5 were 15.97 m (95% loa from -26.42 to -5.52 m) and 20.32 m (95% loa from -30.67 to -9.97 m) smaller,respectively,than those using us pachymetry. conclusions. the tms-5 shows good repeatability and reproducibility for measuring cct and tct in normal subjects but only moderate agreement with us pachymetry results. caution is warranted before using these techniques interchangeably. © 2015 jinhai huang et al.