To evaluate distribution of corneal biomechanical measurements (Corneal Hysteresis=CH, Corneal Resistance Factor=CRF) in normal myopia and myopic-astigmatism population.

One hundred and eighty eyes with myopia and myopic-astigmatism candidated for laser refractive surgery included in this study. Complete examination of anterior and posterior segments , manifest refraction spherical equivalent (MRSE) , Orbscan II and Zywave were performed preoperatively. Ocular Response Analyzer (ORA), was used to measure CH, CRF, Goldman-correlated Intra Ocular Pressure (IOPg) and Corneal Compensated IOP (IOPcc). Distribution of all corneal biomechanical properties and correlation between these parameters and MRSE, age and sex were determined. Statistical analysis was performed using SPSS 17 software and a P-Value less than 0.05 was considered significant

Mean age was 28±7 years. Mean MRSE was -4.21±1.19D. Mean CH, CRF, IOPg and IOPcc was 10±1.28mmHg , 10.16±1.45mmHg , 15.7±2.67mmHg and 16.68±2.41mmHg respectively. 28.4% of all myopic population had CH about 10mmHg, and 71% had CH, 9 up to 11mmHg. CRF in 25.9% of myopic population was 10mmHg, and in 48.7% was 9 up to 11mmHg. There was very poor positive correlation between MRSE & CH (Rs=0.001, P=0.71) and MRSE & CRF ( Rs= 0.01, P=0.18).

Our study demonstrated, the distribution of corneal biomechanical properties (CH , CRF , IOPg, IOPcc) in normal myopia and myopic-astigmatism population in IRAN, and confirmed that, there was no statistically significant correlation between corneal biomechanical properties and MRSE , age and sex.