RESUMO
PURPOSE: To evaluate the effectiveness of cross-linking (CXL) in treating keratoconus eyes with Kmax values ≥58.0 D. METHODS: Retrospective analysis of outcomes of standard Dresden epi-off CXL in progressive keratoconus with preoperative Kmax ≥58.0 Diopters (D). Inclusion criteria were Kmax ≥58.0 D and minimum follow-up of 1 year. Corneal topography and tomography were performed preoperatively and at 1 and 2 years. Sixty-one eyes of 56 patients with mean age of 24.9 ± 8.6 years (mean ± SD, range 12-57 years) had 1-year follow-up. Fifty of these eyes had 2-year follow-up. The definition of progression was an increase in Kmax of ≥1.0 D over 1 year. RESULTS: Mean Kmax was 63.9 ± 6.1 D (mean ± SD, range 58.2-87.0 D) preoperatively (n = 61) and 62.9 ± 5.9 D (range 54.6-82.5 D) after 1 year. This represented a significant decrease in steepness (P = 0.0029). Mean pachymetry decreased significantly from 433.7 ± 44.8 µm preoperatively to 423.0 ± 41.8 µm (P = 0.001) at 1 year. Progression occurred in 14 of the 61 eyes (23%) at 1 year, and 5 (8.2%) steepened more than 2.0 D. In the group with 2-year follow-up, mean Kmax was 63.0 ± 5.0 D (range 58.2-87 D) before CXL and decreased to 61.5 ± 4.8 D (range 53.6-78.3 D) at 2 years (P = 0.001). Nine of the 50 eyes (18%) showed an increase of Kmax of ≥ 1 D. CONCLUSIONS: The incidence of progression (23% at 1 and 18% at 2 years, respectively) is considerably higher than in previously reported results of CXL in eyes with mean Kmax ≥58.0 D. To the best of our knowledge, this study represents the largest number of such steep corneas analyzed with respect to long-term progression after CXL.