Topography-guided Hyperopic LASIK With and Without High Irradiance Collagen Cross-linking: Initial Comparative Clinical Findings in a Contralateral Eye Study of 34 Consecutive Patients

Abstract

To evaluate the safety and efficacy of intrastromally applied collagen cross-linking (CXL) in a comparative contralateral eye study of topography-guided femtosecond laser-assisted hyperopic LASIK. Thirty-four consecutive patients with hyperopia and hyperopic astigmatism elected to have bilateral topography-guided LASIK and were randomized to receive a single drop of 0.1% sodium phosphate riboflavin solution under the flap followed by 3-minute exposure of 10 mW/cm2 ultraviolet A (UVA) light with the flap realigned in one eye (CXL group) and no intrastromal CXL in the contralateral eye (no CXL group). All eyes were treated with the WaveLight FS200 femtosecond laser and WaveLight EX500 excimer laser (Alcon Laboratories Inc). Refractive error and keratometric, topographic, and tomographic measurements were evaluated over mean follow-up of 23 months. Preoperatively, mean spherical equivalent refraction was +3.15 +/- 1.46 diopters (D) and +3.40 +/- 1.78 D with a mean cylinder of 1.20 +/- 1.18 D and 1.40 +/- 1.80 D and mean uncorrected distance visual acuity (UDVA) (decimal) of 0.1 +/- 0.26 and 0.1 +/-0.25 in the CXL and no CXL groups, respectively. At 2 years postoperatively, mean spherical equivalent refraction was -0.20 +/- 0.56 D and +0.20 +/- 0.40 D with mean cylinder of 0.65 +/- 0.56 D and 0.76 +/- 0.72 D and mean UDVA of 0.95 +/- 0.15 and 0.85 +/- 0.23 in the CXL and no CXL groups, respectively. Eyes with CXL demonstrated a mean regression from treatment of +0.22 +/- 0.31 D, whereas eyes without CXL showed a statistically significant greater regression of +0.72 +/- 0.19 D (P = .0001). Topography-guided hyperopic LASIK with or without intrastromal CXL is safe and effective, with greater long-term efficacy (less regression) in eyes with CXL. Our data suggest that the regression seen with hyperopic LASIK may be related to biomechanical changes in corneal shape over time.