[Predictive factors for visual outcome after corneal collagen crosslinking treatment in progressive keratoconus: One-year refractive and topographic results]

To assess the effects of preoperative patient characteristics on clinical outcomes of corneal collagen crosslinking (CXL) in patients with progressive keratoconus.

Fifty-four eyes of 41 patients underwent CXL for progressive keratoconus between June 2011 and December 2012. Corneal topography (Orbscan(®)) was assessed at 1, 3, and 6 months and 1 year after CXL treatment and compared with preoperative data.

A significant improvement in 1-year postoperative best-corrected visual acuity (BCVA) (0.16±0.21 LogMar preoperatively versus 0.09±0.16 LogMar postoperatively, P=0.007) and in 3mm topographic central irregular astigmatism (P=0.04) was demonstrated with CXL. No significant change was noted for refractive astigmatism (P=0.69), or for 1-year postoperative Kmax (48.4 D±4.1 at baseline versus 48.5 D±4.1 postoperatively, P=0.46). Predictive factors for BVCA improvement were low preoperative BCVA, high refractive astigmatism and advanced keratoconus. Predictive factors for stability of postoperative Kmax values were early keratoconus, and central cone ("nipple" morphology of the cone mainly located in the central 3mm of the cornea).

This retrospective study confirms the efficacy of CXL for progressive keratoconus, from a refractive as well as topographic standpoint. While cone localization or its eccentricity seems to explain the variability of CXL efficacy reported in the literature, cone severity appears to be the main predictive factor for a lack of topographic stability after CXL treatment but must be weighted by the preferential localization of the cone (3 or 5mm central corneal zone).