Purpose
Epithelial ingrowth following LASIK surgery has been reported to occur from 0% to 20%, with clinically significant ingrowth as frequently as 8% following a flap re-lifting technique. We performed a retrospective, observational chart analysis focusing on clinical outcomes and incidence of epithelial ingrowth for patients that received LASIK enhancement surgery using the Ziemer LDV CrystalLine® femtosecond laser. We hypothesize that creating a new flap using the femtosecond laser produces clinically favorable refractive outcomes and minimizes the risk of epithelial ingrowth in LASIK enhancement.
Methods
Charts of LASIK enhancements performed from November 2012 through June 2014 were reviewed. A total of 97 eyes from 62 patients were included; 30 males (52 eyes) and 32 females (45 eyes). The average time between original LASIK and enhancement was 10 years. Follow-up end points ranged from one month to one year. The paired t-test was used for statistical analysis.
Results
Highly favorable refractive outcomes were observed following enhancement. The average LogMAR UDVA was improved from 0.373 (SD 0.244) to -0.013 (SD 0.082) following enhancement LASIK. The mean LogMAR UDVA was significantly improved and remained stable throughout follow up (average reduction of -0.385, SEM 0.02, P <0.0001, n = 97). The average depth of the original flap was 130 microns. The depth of the enhancement flap was either 100, 110, or 140 microns (29 cases of 140 flap thickness; below the original flap). Method of original flap creation was noted; Intralase (39), Ziemer (5), and microkeratome (Hansatome 36 and ACS keratome 17). Original LASIK correction was performed on 76 myopic eyes and 21 hyperopic eyes. There were no post-enhancement surgical complications noted, with only one case of clinically insignificant epithelial ingrowth (<1mm in the periphery), not requiring intervention. Our results confirm the hypothesis supporting novel flap creation using the femtosecond laser in LASIK enhancement.
Conclusions
Creation of a new flap using the femtosecond laser for LASIK enhancement produces stable and reproducible improvements in visual acuity with a negligible side effect profile. Our results confirm that the Ziemer LDV CrystalLine® femtosecond laser can be used as a safe and highly efficacious method for new flap creation in LASIK enhancement.