Correlation between Corneal Biomechanical Measurements and Ablation Depth in Customized Photorefractive Keratectomy

The aim of the present study was to evaluate correlation between corneal biomechanical measurements and ablation depth in myopia and myopic-astigmatism after customized photorefractive keratectomy. In 96 eyes with myopia and myopic astigmatism، corneal hysteresis (CH)، corneal resistance factor (CRF)، Goldman-correlated intraocular pressure (IOPg)، and corneal-compensated IOP (IOPcc) before and 3 months after custom PRK were measured. Preoperative manifest refraction spherical equivalent (MRSE)، central corneal thickness (CCT) and ablation depth (AD) were recorded. The changes of parameters after PRK were calculated and correlation between attempted correction of MRSE and AD، between AD and the changes in CH، CRF، IOPg and IOPcc were examined. Preoperative mean of AD was 74. 8131 µ. The preoperative mean of CH and CRF (101. 36 mmHg and 10. 21. 51 mmHg، respectively) was significantly higher than the corresponding postoperative values (7. 551. 81 mmHg and 6. 741. 72 mmHg، respectively) (P<0. 001). The higher attempted correction of MRSE was correlated with higher AD (RS=0. 87، P<0. 001)، higher CH (RS=0. 41، P<0. 001)، and higher CRF (RS=0. 66، P<0. 001). Changes in CH and CRF after customized PRK suggest alteration in corneal biomechanics correlating with attempted correction، and CRF was more affected than CH.