Five-Year Results Of A Prospective, Randomised, Contralateral Eye Trial Of Corneal Crosslinking For Keratoconus

Background Few studies have evaluated corneal crosslinking (CXL) in a prospective, randomised fashion. This study aimed to determine the efficacy and safety of CXL to reduce the progression of keratoconus. Methods Prospective, unmasked, randomised, contralateral eye controlled trial at a tertiary eye centre. Participants: Individuals with bilateral progressive keratoconus. One eye from each subject was randomised to CXL and the contralateral, untreated eye acted as the control. Primary outcome measure: change in maximum keratometry. Secondary outcome measures: uncorrected distance visual acuity, spectacle corrected distance visual acuity, spherical equivalent refraction, simulated keratometry, corneal astigmatism, minimum pachymetry and complications. Results Thirty-eight individuals (mean age 21.1 +/- 6.7 years) were enrolled with one eye treated with CXL. At 5 years, there was a mean decrease in maximum keratometry of treated eyes (-1.45 +/- 2.25 D) compared to an increase among the controls (1.71 +/- 2.46 D; p < 0.001). There were significant differences between the treated and control groups in the mean change of Steep SimK (-1.07 +/- 1.22 vs. 0.96 +/- 1.97 D; p < 0.001), Flat SimK (-0.61 +/- 1.34 vs. 0.43 +/- 1.12 D; p < 0.001), corneal astigmatism (-0.45 +/- 1.31 vs. 0.63 +/- 1.52 D; p < 0.01) and minimum pachymetry (-32.49 +/- 26.32 vs. -13.57 +/- 24.11 mu m; p < 0.01). Complications included sterile infiltrates (n = 2), microbial keratitis (n = 1), persistent corneal haze/scarring at 5 years (n = 4) and loss of >= 2 lines of corrected distance visual acuity (n = 3). Conclusions CXL is an effective and relatively safe intervention to halt or reduce the progression of keratoconus in the majority of eyes for at least 5 years.