Repeatability and agreement of three different ocular biometers including single and dual Scheimpflug cameras

With a wide range of commercially available biometry devices, direct comparisons for agreement, interchangeability and repeatability are needed to enable correct interpretation of measured values.

The purpose of this study was to evaluate the intra-device repeatability and inter-device agreement of three different ocular biometers.

This is a prospective, comparative study conducted at the University Hospital, Goethe University, Frankfurt, Germany. Included were eyes with a cataract which showed no other pathology. One eye per patient was randomly selected and 3 consecutive measurements were taken with the IOLMaster 700, Galilei G6, and Pentacam AXL. Repeatability and agreement were evaluated for simulated keratometry (simK), astigmatism (simA) and its axis, total keratometry (TC), axial length (AL), anterior chamber depth (ACD), and pachymetry (CT).

simK, TC, AL, and CT show very high repeatability with an intra-class correlation (ICC) of > 0.9 and a COV < 0.5 each. Means of the measurements were significantly different between the devices for simK, AL, and TC (p < 0.05). ACD and simA also showed a high ICC, but a lower agreement between the devices. Fixed biases shown by Bland-Altman plots for simK seem to indicate that the values are not interchangeable.

Even though very high repeatability and agreement for most of the measured variables was observed with all three devices, fixed differences indicate that measured values are not completely interchangeable between the devices.