We would like to thank the authors for their comment on our recently published randomized transepithelial corneal cross-linking (CXL) study, and for their suggestions for failure of the transepithelial CXL technique.

Regarding the comment relating to the presence of dextran in transepithelial solution and the reduced passage through the epithelium, we do not believe that Wollensak and Iomdina related this finding to dextran T-500 specifically. We believe they stated that only with the addition of benzalkonium chloride to riboflavin with dextran T-500, partial diffusion through the epithelium was noted in the transepithelial (rabbit) treatment group. On the other hand, Filippello and associates found reduced keratometry values 1 year after transepithelial CXL with Ricrolin TE (containing dextran T-500). Hypoosmolar transepithelial riboflavin solutions were not available to us at the start of our study.

In Yuksel and associates’ other comment relating to ultraviolet-A (UVA) dosage, they state the point that longer irradiation times can be considered owing to the approximately 20% of UVA uptake by the corneal epithelium before it reaches the stroma. However, currently there is no standard protocol available for the minimally required UVA time in transepithelial CXL. In addition, by the time our study started, high-fluence or accelerated CXL procedures were not available to us and therefore we administered the Ricrolin TE drops according to the instructions of the manufacturer (which contained no information on the UVA duration and/or intensity).

The problem of the ineffectiveness after transepithelial CXL is probably the combination of the absence of sufficient riboflavin uptake into the stroma and the lacking duration or intensity of the UVA light. These issues remain to be established.