Long-term visual, anterior and posterior corneal changes after crosslinking for progressive keratoconus

Aim To evaluate the long-term outcomes of corneal cross-linking (CXL) in patients with progressive keratoconus. Method In this retrospective non-comparative study, forty-five eyes of 31 patients with progressive keratoconus were treated with 30 min "epi-off" corneal cross-linking. The visual, refractive, topographic and tomographic outcomes were evaluated preoperatively and at least 10 years after cross-linking. Results Ten years post-corneal cross-linking, the mean anterior maximum keratometry decreased (-2.10 +/- 3.25 D, P = 0.0001). Conversely, the posterior maximum keratometry increased (6.38 +/- 9.79 D, P = 0.065). Both uncorrected and corrected distance visual acuity improved (LogMAR -0.08 +/- 0.30) and (LogMAR -0.05 +/- 0.21), respectively (P > 0.05, both). A statistically significant hyperopic shift was observed postoperatively (0.70 +/- 1.31 D, P = 0.0009). The anterior topographic cylinder values revealed no change (-0.17 +/- 1.31 D, P = 0.3), whereas the mean posterior cylinder values decreased (absolute value increased) significantly compared to baseline from -1.31 +/- 0.97 D to -1.82 +/- 1.78 D, (P < 0.05). The minimum corneal thickness values decreased significantly (-35.11 +/- 48.63 mu m, P = 0.0001). Four eyes (8.8%) showed more than 1 D increase in the anterior maximum keratometry. Conclusion This protocol and duration of Epi-off corneal cross-linking was found to be effective in halting keratoconus progression over the follow up period (10 years). Anterior corneal flattening and a hyperopic shift were observed. A statistically significant increase in the posterior corneal cylinder was observed. Although, not reaching statistical significance, the logMAR uncorrected and corrected visual acuity were improved.