Clinical Optometry (Sep 2022)
Daily Variations of Corneal White-to-White Diameter Measured with Different Methods
Abstract
Stefan Bandlitz,1,2 Makram Nakhoul,3 Konstantin Kotliar3 1Höhere Fachschule für Augenoptik Köln (HFAK), Cologne School of Optometry, Cologne, Germany; 2School of Life and Health Sciences, Aston University, Birmingham, UK; 3Department of Medical Engineering and Technomathematics, FH Aachen University of Applied Sciences, Campus Jülich, Jülich, 52428, GermanyCorrespondence: Konstantin Kotliar, Department of Medical Engineering and Technomathematics, FH Aachen University of Applied Sciences, Campus Jülich, Heinrich-Mussmann-Str. 1, Jülich, 52428, Germany, Tel +49 241 6009-53812, Fax +49 241 6009-53222, Email [email protected]: A precise determination of the corneal diameter is essential for the diagnosis of various ocular diseases, cataract and refractive surgery as well as for the selection and fitting of contact lenses. The aim of this study was to investigate the agreement between two automatic and one manual method for corneal diameter determination and to evaluate possible diurnal variations in corneal diameter.Patients and Methods: Horizontal white-to-white corneal diameter of 20 volunteers was measured at three different fixed times of a day with three methods: Scheimpflug method (Pentacam HR, Oculus), placido based topography (Keratograph 5M, Oculus) and manual method using an image analysis software at a slitlamp (BQ900, Haag-Streit).Results: The two-factorial analysis of variance could not show a significant effect of the different instruments (p = 0.117), the different time points (p = 0.506) and the interaction between instrument and time point (p = 0.182). Very good repeatability (intraclass correlation coefficient ICC, quartile coefficient of dispersion QCD) was found for all three devices. However, manual slitlamp measurements showed a higher QCD than the automatic measurements with the Keratograph 5M and the Pentacam HR at all measurement times.Conclusion: The manual and automated methods used in the study to determine corneal diameter showed good agreement and repeatability. No significant diurnal variations of corneal diameter were observed during the period of time studied.Keywords: corneal diameter, white-to-white, diurnal variation, Scheimpflug imaging, placido based topography, slitlamp
