Effect of Photorefractive Keratectomy with Mitomycin-C on Corneal Biomechanical Features
Purpose: To evaluate corneal biomechanical properties and intraocular pressure (IOP) after photorefractive keratectomy (PRK) with or without mitomycin-C (MMC) 0.02% in myopic eyes. Methods: In this prospective, comparative interventional case series, 33 right eyes of 33 patients were included. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated IOP (IOPg), and cornea-compensated IOP (IOPcc) were measured using ocular response analyzer (ORA) before and 3 months after PRK. IOP was determined using Goldmann applanation tonometry (GAT). The pre- and post-operative values were compared. Effects of ablation depth, optical zone (OZ) and duration of MMC application on corneal biomechanics were examined. Results: Mean ablation depth was 56.6 +/- 20.8 mu m. Postoperatively, there was a significant reduction in corneal biomechanics and IOP readings by the GAT and ORA. Ablation depth was significantly associated with percentage change in CH (P = 0.021), CRF (P = 0.001), and IOP GAT (P < 0.001). However, the size of OZ and duration of MMC application did not have any correlation with these parameters. The percentage change in IOP GAT and IOPg but not IOPcc was significantly associated with percentage change in CH and CRF. Conclusions: The corneal biomechanical strength significantly reduced after PRK which is associated to the amount of ablation. However, the OZ and the duration of MMC application did not affect these parameters. IOPcc appeared to be less dependent on altered corneal properties compared to IOPg and IOP GAT.