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First Author: M.Abrishami IRAN
Co Author(s): M. Reza Sedaghat M. Sharepoor S. Hassanzadeh
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The aim of this study was to determine the relationship between corneal hysteresis (CH) and the corneal resistance factor (CRF), which are novel methods of analyzing ocular rigidity/elasticity, and various corneal characteristics, mainly corneal volume in normal subjects.
Khatamal-Anbia Eye Hospital, Eye Research Center , School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
This cross-sectional study included 500 normal eyes of volunteers. An Ocular Response Analyzer was used to measure CH and CRF. Patient age and the Pentacam-measured corneal volume (CV), posterior elevation, anterior elevation, corneal curvature, central corneal thickness (CCT), corneal thickness of apex (CTA), and corneal thinnest thickness (CTT) were compared with CH and CRF. Statistical significance was defined at the P < 0.05 level.
The mean hysteresis for all eyes was 9.9 ±1.4 mmHg and the mean CRF was 10.1 ±1.6 mmHg. The mean corneal volumes of the 3, 5, 7, and 10 mm zones for all eyes were 3.8 ±0.2 mm3, 11.2 ±0.6 mm3, 24.3 ±1.4 mm3, and 60.1 ±3.5 mm3, respectively. The relationship between CV and the hysteresis or CRF was significant in all zones. The CV of the 7-mm zone had the strongest correlation with corneal hysteresis (r = 0.438) and the CV of the 5-mm zone had the strongest correlation with CRF (r = 0.574).
CH and CRF correlate with CV, and the relationship between CV and CRF is stronger than that between CV and CH. The CV may prove valuable for determining patient qualification, predicting the outcome of refractive surgery, and in other cases in which corneal biomechanics are important.