 Four ORA measurements were taken per eye and the mean value was recorded for each parameter CH, CRF and IOPcc. Central corneal thickness CCT was measured by ultrasound pachymetry DGH Technology, INC, Exton, PA and the average of three measurements was recorded. All study measurements were performed by the same trained observer RM, with the same equipment and at the same time of day. All of the equipment needed for this research was calibrated prior to each use. 