[Corneal riboflavin/UV-A collagen cross-linking (CXL) in keratoconus: two-year results]

Photochemical collagen cross-linking with riboflavin and UV-A radiation (CXL) is reported to strengthen the cornea in keratoconus. This retrospective longitudinal study analyses the outcomes 2 years after CXL.

46 eyes of 45 patients with keratoconus stadium 1 to 3 with disease progression confirmed by topography or patient history underwent CXL after corneal abrasion. Follow-up over 2 years included biomicroscopy, visual acuity, topography, pachymetry, and endothelial cell count. Changes were analysed with paired Student's t test or Wilcoxon signed-rank test.

All patients showed initial haze (maximum 2 + ) and increase of epithelial surface irregularity resulting in temporarily reduced vision, but this resolved within 3 months. Medium visual acuity (logMAR) improved from 0.29 to 0.20 (p = 0.019, 12 months postop) or to 0.24 (p = 0.200; 24 months postop). This corresponds to an improvement (≧ 1 line) in 51 % of eyes, a loss of vision in 27 %. Mean maximum radius of curvature was reduced by 1.24 diopters (D) (95 % confidence interval 0.05 - 2.43; p = 0.042) in the first year, and reduced by 1.23 D (0.42 - 2.05; p = 0.004) at 2 years after CXL. Mean pachymetry showed a significant reduction of 23 µm (p = 0.0004, 1 year postop), endothelial cell count showed no significant change.

In spite of a temporary reduction in vision, long-term outcome showed recovery or increase in visual acuity in the majority of eyes. Topography data indicate a stabilisation of keratoconus after CXL.