title: Comparison of prophylactic higher fluence corneal cross-linking to control, in myopic LASIK, one year results.
abstract: OBJECTIVE
  To compare 1-year results: safety, efficacy, refractive and keratometric stability, of femtosecond myopic laser-assisted in situ keratomileusis (LASIK) with and without concurrent prophylactic high-fluence cross-linking (CXL) (LASIK-CXL).
  
  
  METHODS
  We studied a total of 155 consecutive eyes planned for LASIK myopic correction. Group A represented 73 eyes that were treated additionally with concurrent prophylactic high-fluence CXL; group B included 82 eyes subjected to the stand-alone LASIK procedure. The following parameters were evaluated preoperatively and up to 1-year postoperatively: manifest refractive spherical equivalent (MRSE), refractive astigmatism, visual acuity, corneal keratometry, and endothelial cell counts. We plotted keratometry measurements pre-operatively and its change in the early, interim and later post-operative time for the two groups, as a means of keratometric stability comparison.
  
  
  RESULTS
  Group A (LASIK-CXL) had an average postoperative MRSE of -0.23, -0.19, and -0.19 D for the 3-, 6-, and 12-month period, respectively, compared to -6.58±1.98 D preoperatively. Flat keratometry was 37.69, 37.66, and 37.67 D, compared to 43.94 D preoperatively, and steep keratometry was 38.35, 38.36, and 38.37 D, compared to 45.17 D preoperatively. The predictability of Manifest Refraction Spherical Equivalent (MRSE) correction showed a correlation coefficient of 0.979. Group B (stand-alone LASIK) had an average postoperative MRSE of -0.23, -0.20, and -0.27 D for the 3-, 6-, and 12-month period, respectively, compared with -5.14±2.34 D preoperatively. Flat keratometry was 37.65, 37.89, and 38.02 D, compared with 43.15 D preoperatively, and steep keratometry was 38.32, 38.57, and 38.66 D, compared with 44.07 D preoperatively. The predictability of MRSE correction showed a correlation coefficient of 0.970. The keratometric stability plots were stable for the LASIK CXL group and slightly regressing in the standard LASIK group, a novel stability evaluation metric that may escape routine acuity and refraction measurements.
  
  
  CONCLUSIONS
  Application of prophylactic CXL concurrently with myopic LASIK surgery appears to contribute to improved refractive and keratometric stability compared to standard LASIK. The procedure appears safe and provides a new potential for LASIK correction.
authors.affiliation: LaserVision.gr Clinical and Research Eye Institute, Athens, Greece ; New York University Medical School, New York, NY, USA.
authors.forename: Anastasios John
authors.initials: AJ
authors.lastname: Kanellopoulos
authors.affiliation: LaserVision.gr Clinical and Research Eye Institute, Athens, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Asimellis
authors.affiliation: LaserVision.gr Clinical and Research Eye Institute, Athens, Greece.
authors.forename: Costas
authors.initials: C
authors.lastname: Karabatsas
keywords: LASIK-CXL; LASIK-Xtra; accelerated high-fluence collagen cross-linking; femtosecond myopic LASIK; high myopia; myopic LASIK regression