Corneal Collagen Cross-Linking for Ectasia after LASIK and Photorefractive Keratectomy Long-Term Results

Purpose: To report the long-term results of corneal collagen cross-linking (CXL) in ectasia after LASIK and photorefractive keratectomy (PRK). Design: Retrospective, interventional cases series. Participants: Twenty-six eyes of 26 patients (18 male, 8 female) with postoperative ectasia after LASIK (23 eyes) and PRK (3 eyes) were included with a mean age of 35 +/- 9 years at the time of treatment and a mean follow-up of 25 months (range, 12-62 months). Methods: All consecutive patients treated with CXL for progressive ectasia after LASIK or PRK at the Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland between 2004 and 2010 were included. Main Outcome Measures: Corrected distance visual acuity (CDVA), maximum keratometry readings (K-max), minimum radius of curvature (R-min), and 6 corneal topography indices were assessed in this study. Results: Mean CDVA before CXL was 0.5 logarithm of the minimum angle of resolution (logMAR) units, which improved to a mean of 0.3 logMAR units (P<0.001). Corrected distance visual acuity improved 1 line or more in 19 cases and remained unchanged in 7 patients. Mean K-max after CXL of 50.9 +/- 4.9 diopters (D) was significantly lower (P<0.001) than mean pre-CXL K-max of 52.8 +/- 5 D. The R-min after CXL was increased significantly (P = 0.006), whereas the index of surface variance (P = 0.03), the index of vertical asymmetry (P = 0.04), the keratoconus index (P = 0.03), and the central keratoconus index (P = 0.016) were reduced significantly. Conclusions: Ectasia after LASIK and PRK was arrested by CXL with stabilization or improvement of CDVA and K-max after a mean follow-up of 25 months. There were improvements in 4 topography indices, suggesting a more regular corneal surface.