Abstract
Background and Objectives: In this study we evaluated distribution of corneal biomechanical measurements including (Corneal Hysteresis = CH and Corneal Resistance Factor = CRF) in a group of normal myopia and myopic-astigmatism population.
Materials and Methods: 180 eyes with myopia and myopic-astigmatism candidate for laser refractive surgery included in this cross-sectional study. Complete examination of anterior and posterior segments, manifest refraction spherical equivalent (MRSE), OrbscanII and Zywave aberrometry 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.
Results: Mean age was 28+/-7 years. Mean MRSE -4.21 +/- 1.19 D. Mean CH, CRF, IOPgand IOPcc were, 10 +/- 1.28 mmHg , 10.16 +/- 1.45 mmHg , 15.7 +/- 2.67 mmHg and 16.68 +/- 2.41 mmHg 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).
Conclusion: Our study demonstrated the distribution of corneal biomechanical properties in normal myopia and myopic – astigmatism population who were candidates for laser vision correction. This study revealed that, there was no statistically significant correlation between corneal biomechanical properties and MRSE, age and sex.