Impact of Keratoconus Stage on Outcome After Corneal Crosslinking

Abstract

Background: This study aimed to analyze if the outcome after corneal crosslinking (CXL) in progressive keratoconus patients depends on the stage in which the procedure is performed. This knowledge would help to improve success of CXL and facilitate defining surgery indications in those patients.Methods: In this retrospective study, 124 consecutive eyes of 100 patients with progressive keratoconus undergoing corneal CXL at the University Eye Hospital Tübingen were included. The eyes were graded according to modified Krumeich stages depending on induced myopia or astigmatism, corneal radii, minimum corneal thickness, and morphological changes. The observation period took place from November 2008 to September 2018. Preoperatively, 12 and 24 months after CXL, the best corrected visual acuity (BCVA) was determined and astigmatism as well as keratometric parameters (Kmax, Kmin, central corneal thickness (CCT), minimum corneal thickness (MCT)) were measured by means of a Scheimpflug camera system.Results: BCVA results showed significant differences between the modified Krumeich stages 12 months (p=0.014) and 24 months postoperatively (p=0.032). Also, astigmatism differed significantly among the stages 24 months after CXL (p=0.023); however, after 12 months, no significant differences between the groups were detectable. In terms of Kmax, Kmin, CCT, and MCT, no significant differences between the Krumeich stages were observed.Conclusions: BCVA showed a significantly higher improvement after CXL in the early stage of keratoconus compared to a higher stage. However, the postinterventional keratometric values did not differ significantly between the different modified Krumeich stages. The significantly higher improvement in BCVA after CXL in the early stage might indicate that earlier intervention provides a higher subjective benefit to the individual. Further studies with larger sample sizes are needed to confirm these findings.