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Repeatability of ocular biomechanical data measurements with a Scheimpflug-based noncontact device on normal corneas.

PURPOSE
To analyze the repeatability of a new device measuring ocular biomechanical properties, central corneal thickness (CCT), and intraocular pressure (IOP) and to investigate these parameters and their correlations in healthy eyes.


METHODS
Three consecutive measurements were performed on each eye using the CorVis ST device (Oculus Optikgeräte, Inc., Wetzler, Germany). Ten specific parameters, CCT, and IOP were measured. Biometric data were recorded with IOLMaster (Carl Zeiss Meditec, Jena, Germany).


RESULTS
This study comprised 75 eyes of 75 healthy volunteers (mean age: 61.24 ± 15.72 years). Mean IOP was 15.02 ± 2.90 mm Hg and mean CCT was 556.33 ± 33.13 μm. Intraclass correlation coefficient (ICC) was 0.865 for IOP and 0.970 for CCT, and coefficient of variation was 0.069 for IOP and 0.008 for CCT. ICC was 0.758 for maximum amplitude at highest concavity and 0.784 for first applanation time, and less than 0.6 for all other parameters. The device-specific data showed no significant relationship with age and axial length. Flattest and steepest keratometric values and IOP showed a significant correlation with the 10 device-specific parameters.


CONCLUSIONS
The CorVis ST showed high repeatability for only IOP and pachymetric values. Single measurements are not reliable for the 10 device-specific parameters. The device allows for conducting clinical examinations and screening for surgeries altering ocular biomechanical properties with some form of averaging of multiple measurements.