Evolution of corneal flattening after repeated corneal cross-linking during a 6-year follow-up.

To report the evolution of corneal flattening after repeated corneal cross-linking (CXL) in a patient with progressive keratoconus during a 6-year follow-up. Case report. A 27-year-old female underwent CXL for progressive keratoconus. Postoperatively, corneal topography revealed keratoconus progression with an increase of 1.20 diopters (D) in maximum keratometry (Kmax) and CXL was repeated. After the second treatment, a continuing significant corneal flattening (up to 16.00 D in Kmax) was observed during the first 5 years followed by stabilization during the last sixth year of follow-up. Both uncorrected and corrected distance visual acuity were improved while corneal thickness was decreased. There were no complications such as corneal opacification or endothelial cells decrease during the follow-up period. Repeated CXL can induce an excessive corneal flattening more pronounced during the first years of follow-up followed by stabilization thereafter.