Effects of corneal collagen crosslinking on corneal topographic indices in patients with keratoconus.

Objectives: To evaluate the effects of corneal crosslinking (CXL) on corneal topographic indices in patients with progressive keratoconus using Scheimpflug imaging system.

Methods: This retrospective study comprised 59 eyes of 47 patients who underwent CXL treatment for confirmed progressive keratoconus. Changes in corrected distance visual acuity (CDVA, logMAR equivalent), maximum keratometry (K), and corneal topographic indices included index of surface variance (ISV), index of vertical asymmetry, keratoconus index, center keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration, and minimum radius of curvature (Rmin) were analyzed at 1-year follow-up. Correlations between topographic indices and visual acuity were sought.

Results: The study included 59 eyes of 47 patients with progressive keratoconus. The mean CDVA (P<0.001), maximum K (P<0.001), ISV, Rmin, and CKI (P =0.013, P < 0.001, respectively) significantly improved after CXL treatment. Moreover, we found a significant negative correlation between the change in IHA value and the improvement in CDVA (r = -0.351; P = 0.006).

Conclusions: In patients with progressive keratoconus, cornea becomes more optically regular after CXL treatment. Changes in topographic indices might be valuable to follow-up the normalization of keratoconic cornea during the postoperative course and superior-inferior height symmetry seems to be associated with visual improvement.