The Effect Obl During Femtosecond Laser Corneal Flap Is Forming

To determine the frequency of OBL formation, the dependence of OBL on corneal thickness, the effect of OBL on the refractive result of FemtoLASIK

Method Femtosecond laser- assisted Lasik using IntraLase iFS+VISX Star S4IR (bed energy 0.70 µJ, spot separations 7 µm,) and flap parameters (depth 90-110 µm, diameter 9.2 mm, hinge position superior, pocket 170 µm), the minimum residual corneal thickness is 300 µm

All patients had standard diagnostics before and after refractive surgery. 174 patients (348 eyes) with myopia from -1.25 D to -8.0 D (-4,65±0,7 D), astigmatism up to -3.0 D (-1,36±0,5 D), and corneal thickness from 481 to 604 µm (536±26 µm) were selected for the study. OBL extending to an 8-mm ablation zone of the corneal stroma was considered significant

During creating a flap the effect OBL was in 66 eyes (18.9%) of 348 eyes studied. The study noted a direct correlation between the thickness of the cornea and the incidence of OBL formation - the thicker the cornea, the greater the proportion of cases with effect OBL. An increase in the incidence of OBL on the periphery of the cornea was noted with incorrect decentralized installation of the vacuum ring and applanation cone. There were no statistically significant differences in visual acuity and spherical equivalent in both groups of patients after Femto-Lasik

Diagnostic assessment before surgery of the patient's corneal thickness and correct cone applanation technique allows one to predict an increased risk of OBL and make a personalized choice of FemtoLASIK parameters.