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Comparison of Data From the Rostock Cornea Module of the Heidelberg Retina Tomograph, the Oculus Pentacam, and the Endothelial Cell Microscope

Purpose: The aim of this study was to validate data arising from the Rostock Cornea Module (RCM) of the Heidelberg Retina Tomograph. Morphological parameters of the cornea were analyzed according to their dependency on patient's age. Methods: RCM measurements of 60 healthy eyes within 2 different age groups (group 1 <35 years, group 2 >50 years) were compared with the corneal thickness determined by the Oculus Pentacam and the endothelial cell density measured by the Tomey endothelial microscope, EM-2000. Results: The mean corneal thickness measured with the Heidelberg Retina Tomograph/RCM was 517 ± 31 μm and 542 ± 30 μm with the Oculus Pentacam (correlation coefficient, R = 0.78). Group 1 showed a corneal thickness of 509 ± 24μm with the RCM and 531 ± 27μm with the Pentacam. In group 2, the corneal thickness was 525 ± 34 μm and 553 ± 29 μm, respectively. A significant increase in corneal thickness for older patients could be shown. The differences between the methods and the age groups were statistically significant (P < 0.0001). The average endothelial cell density measured with the RCM was 2779 ± 472 cells per square millimeter. Between the age groups and the methods (RCM and endothelial microscope), no statistically significant differences could be found. Cell densities for the epithelial cell layers and keratocytes showed no significant correlation with age and sex of the patients. Conclusions: The RCM provides a reliable procedure for the evaluation of all corneal layers including morphological parameters. Endothelial cell densities either determined with the RCM or the EM-2000 are generally comparable to each other and showed no significant differences. It is suggested that lower corneal thickness measurements of the RCM can be caused by pressure during examination. An increased corneal thickness in the older group could be determined with the RCM and the Oculus Pentacam.