 The purpose of this retrospective study is to assess corneal changes keratometry, pachymetry and change in visual acuity VA in keratoconus patients after unilateral crosslinking treatment compared to the untreated fellow eye. The corneal measurements obtained preoperatively and 2 to 14 months postoperatively using a Pentacam rotating scheimpflug camera are analyzed. Furthermore, pre-existing or actual ocular pathology orand ocular surgeries as potential factors involved in treatment outcome are also evaluated. 