Function and Disability Journal (Aug 2018)
Corneal Biomechanical Characteristics and Their Correlation in an Iranian Adult Myopic Population
Abstract
Background and Objective: Corneal biomechanics is a branch of science that studies deformation and equilibrium of corneal tissue under the application of any force. The objective of the study was to determine the normal values of corneal biomechanical characteristics including corneal resistant factor (CRF) and corneal hysteresis (CH) in an Iranian adult myopic population and their associations with age, gender and ocular biometrical components. Methods: The number of 480 eyes of 480 patients (mean age: 26.73 ± 4.9) with myopia and myopic astigmatism were included in this study. Ocular Response Analyzer (ORA) was used to measure corneal biomechanical metrics of CH and CRF. Corneal topographic and pachymetric measurements were obtained using Pentacam Scheimflug topographer. Results: The means of CH and CRF were 10.28 ± 1.49 and 10.49 ± 1.61, respectively. Females showed higher CH and CRF values compared to males (CH: 10.55 ± 1.36 vs. 9.72 ± 1.57, CRF: 10.73 ± 1.46 vs. 9.94 ± 1.74). The CH was significantly positively correlated with central corneal thickness (CCT) and corneal volume (CV) and significantly negatively correlated with horizontal and vertical radius of curvatures of the back corneal surface and horizontal radius of curvature of the front corneal surface. The CRF had a significant positive correlation with CCT and CV, whereas significant negative correlations were found between CRF and horizontal and vertical radius of curvatures of the back corneal surface. In the linear multiple regression model, CH was only significantly associated with CV; likewise, CRF showed significant association only with CCT. Conclusion: The mean values of CH and CRF in Iranian population were higher than values reported in East Asian countries, comparable to or higher than values in USA and UK populations. From various ocular dimensions, CH was significantly associated with CV; whereas, CRF was significantly associated with CCT.
