The authors report on the reproducibility and repeatability of corneal thickness measurements using three different Scheimpflug imaging cameras (Pentacam, Sirius and Galilei) and one Fourier-domain optical coherence tomography (OCT) system (RTvue-100). The rationale for this study is that corneal thickness measurements using ultrasonic pachymetry are not entirely reliable due to the requirement for contact with the cornea and dependence on operator skill. The four different instruments stated above all offer the possibility of non-contact corneal thickness measurements, not just at the centre, but also at the mid-periphery and periphery. The study was designed in a way to evaluate the intraobserver variability, interobserver variability and intersession variability for these four instruments. Sixty-six eyes from 66 healthy subjects were recruited for the study. In terms of intraobserver repeatability, interobserver repeatability and intersession repeatability, the Galilei performed best while the Pentacam performed worst. Overall, the repeatability and reproducibility was high for all four instruments at all corneal areas measured apart from the mid-peripheral superior quadrant. The authors did not compare these corneal measurements versus measurements taken by ultrasonic pachymetry, and so agreement could not be evaluated. Nevertheless, this study shows that these imaging methods can provide non-contact corneal thickness measurements that are highly repeatable and reproducible.

A comparison between Scheimpflug imaging and optical coherence tomography in measuring corneal thickness.
Huang J, Ding X, Savini G, Pan C, et al.
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Brian Ang

Royal Victorian Eye and Ear Hospital, Melbourne, Australia

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