Does photorefractive keratectomy with mitomycin results in less weakening effect on corneal biomechanics compared to thin-flap Lasik procedure in mild to high myopia? An Ocular Response Analyzer study

Abstract

Purpose To understand the changes in corneal biomechanics studied by Ocular Response Analyzer after thin-flap Lasik technique compared with photorefractive keratectomy (PRK) with mitomycin C in mild to high myopia to decrease the risk of ectasia. Patients and methods Forty eyes of 24 myopic patients with mild to severe myopia were divided into two groups; group A (included 20 eyes treated by thin-flap Lasik technique and group B (included 20 eyes treated by PRK with application of mitomycin C 0.02%). Patients were examined preoperatively and postoperatively. For the Ocular Response Analyzer, corneal hysteresis (CH), corneal resistance factor (CRF), and the keratoconus suspect (KS) were studied. Collected data were subjected to statistical analyses. Results In this study, postoperatively, a highly significant decrease (P0.05) between both groups regarding postoperative changes in CH, CRF, and KS%. A highly significant correlation (P<0.01) existed between total corrected spherocylindrical refraction and the postablative decrease in CH as well as in CRF. A statistically significant correlation (P<0.05) existed between the total corrected spherocylinderical refraction and the postablative increase in the KS% in both groups. Conclusion Both thin-flap Lasik and PRK with mitomycin for mild to high myopia resulted in significant comparable reduction in the corneal biomechanical properties, the magnitude of which is highly dependent on the extent of correction.

Keywords

• corneal hysteresis
• corneal resistance factor
• keratoconus suspect percentage
• mild to high myopia
• photorefractive keratectomy mitomycin
• thin-flap Lasik