Eight-year results of LASIK with or without combined accelerated crosslinking in highly myopic eyes

To analyze the 8-year results of femtosecond laser-assisted in situ keratomileusis (LASIK) combined with simultaneous accelerated corneal crosslinking (LASIK-Xtra) compared with conventional LASIK (convLASIK).

Department of Ophthalmology, Goethe-University, Frankfurt am Main, Germany.

Prospective, randomized fellow eye-controlled clinical trial.

Patients who received randomized treatment with the LASIK-Xtra (30 mW/cm 2 , 90 seconds with continuous UV-A) in 1 eye and convLASIK in the fellow eye were subjected 1 year (pos1y), and 8 years postoperatively (pos8y) to subjective refraction, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), endothelial cell count (ECC), biomechanical evaluation, and tomographic examination.

26 eyes (-7.07 ± 1.86 diopter [D]) from 13 patients (mean age 30.7 ± 10.4 years) were included. UDVA and CDVA were insignificantly different at pos1y and pos8y between convLASIK and LASIK-Xtra (each P > .28). The safety index at pos8y was 1.09 for convLASIK and 1.15 for LASIK-Xtra ( P = .799), and the efficacy index 0.91 and 0.94 ( P = .875), respectively. Significant myopic shift in spherical equivalent between pos1y (-0.30 ± 0.40 D) and pos8y (-0.80 ± 0.86 D) was found in the convLASIK group ( P = .018), compared the LASIK-Xtra group (-0.25 ± 0.49 D and -0.40 ± 0.86 D; P = .261), respectively. However, these refractive changes cannot be fully attributed to corneal alterations alone and may also reflect other factors. Insignificant differences in mean keratometry, corneal thickness, and ECC were found at pos8y ( P > .05). The stress-strain index was the only biomechanical parameter that was significantly higher in the LASIK-Xtra group at pos8y ( P = .034).

After 8 years, no substantial disparities in efficacy and safety indices were observed between the 2 groups. There were no substantial differences in most of the evaluated postoperative corneal biomechanical parameters between the 2 groups. However, these findings need to be validated by further studies with larger sample sizes.