Corneal Cross-linking to Halt the Progression of Keratoconus and Corneal Ectasia: Seven-Year Follow-up

Abstract

Purpose: To determine long-term efficacy and safety of riboflavin/ultraviolet A corneal cross-linking (CXL).

Design: Prospective cohort study.

Methods: Thirty-six patients (36 eyes) who underwent epithelium-off CXL at a University Hospital (Guy's and St Thomas' National Health Service Foundation Trust) 6-8 years previously were examined. The main outcome measures were refractive error, visual acuity, corneal topographic keratometry, ultrasonic pachymetry, and topography-derived corneal wavefront.

Results: At 7 years compared to preoperative values, mean spherical equivalent refractive error (SEQ) increased by +0.78 diopter (D) (P < .005) and mean simulated topographic keratometry (SimK) and mean maximum keratometry (Kmax) reduced by -0.74 D (P < .0001) and -0.91 D (P < .0001), respectively. Uncorrected distance acuity (UCDA) (P < .0005) and corrected distance acuity (CDVA) (P < .0001) had improved and root mean square (RMS) (P < .0005), coma (P < .0005), and secondary astigmatism (P < .005) lessened. At 7 years compared to 1 year, CDVA improved (P < .05); mean SimK (P < .0005) and mean Kmax (P < .005) reduced by -0.45 D and -0.56 D, respectively; and RMS (P < .0005) and coma (P < .0005) decreased. At 7 years compared to 5 years, CDVA improved (P < .05) and trefoil reduced (P < .05). No treated eyes progressed. In 29 initially untreated fellow eyes mean SimK increased by +0.54 D (P < .02), mean Kmax by +0.87 D (P < .05), and refractive astigmatism increased (P < .0005).

Conclusions: Following corneal cross-linking, improvements in topographic and wavefront parameters evident at 1 year were seen to continue to improve at 5 years and were maintained at 7 years. No treated eyes progressed over the 7-year follow-up period.