Abstract
PurposeTo compare corneal thickness measurements using Pentacam (Oculus, Germany), Sirius (CSO, Italy), Galilei (Ziemer, Switzerland), and RTVue-100 OCT (Optovue Inc., USA).MethodsSixty-six eyes of 66 healthy volunteers were enrolled. Three consecutive measurements were performed with each device. The mean value of the three measurements was used for subsequent analysis. Central corneal thickness (CCT), thinnest corneal thickness (TCT), and midperipheral corneal thickness (MPCT; measured at superior, inferior, nasal, and temporal locations with a distance of 1 mm (CT2mm) or 2.5 mm (CT5mm) from the corneal apex) were analyzed. Differences and agreement between measurements were assessed using the repeated-measures analysis of variance (ANOVA) and Bland-Altman analyses, respectively.ResultsStatistically significant differences (p<0.001) among the four devices were revealed in CCT, TCT and CT2mmmeasurements. The CCT, TCT, and CT2mm values were ranked from the thickest to the thinnest as follows: Galilei>Sirius>Pentacam>RTVue OCT. For these measurements, agreement between measurements by Sirius and Pentacam was good, whereas Galilei overestimated and RTVue underestimated corneal thickness compared to Sirius and Pentacam. As regards CT5mm measurements, Pentacam provided the largest values, whereas RTVue OCT yielded the smallest values. Agreement of the CT5mm measurements was good between the Pentacam, Sirius, moderate between Galilei and the other two Scheimpflug systems, and poor between the RTVue OCT and the remaining devices.ConclusionsThe Pentacam and Sirius can be used interchangeably for CCT measurements, while the Galilei and RTVue systematically over- and underestimate CCT, respectively. The three Scheimpflug cameras, but not the RTVue, may be used interchangeably for MPCT measurements.
Highlights
Corneal thickness measurement is crucial in many clinical and research applications [1]
The repeatability and reproducibility of corneal thickness measurements have been reported to be good with the use of these instruments [13,14,15,16], and the reliability of central corneal thickness (CCT) and thinnest corneal thickness (TCT) measurements has been shown to be higher than the peripheral corneal thickness measurements [16,17]
Agreement between CCT, TCT, and CT2mm measurements obtained by the four systems
Summary
Corneal thickness measurement is crucial in many clinical and research applications [1]. The determination of central corneal thickness (CCT) is important for the planning of refractive surgery, diagnosis of glaucoma, and monitoring of corneal edema [2,3,4,5,6,7]. Ultrasonic pachymetry (USP) is the gold-standard technique for measuring corneal thickness. It requires contact with the cornea and topical anesthesia, which may cause patient discomfort and a decrease in reliability. The repeatability and reproducibility of corneal thickness measurements have been reported to be good with the use of these instruments [13,14,15,16], and the reliability of CCT and thinnest corneal thickness (TCT) measurements has been shown to be higher than the peripheral corneal thickness measurements [16,17]
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