We would like to express our appreciation for Zygoura and associates’ letter. It is encouraging to note that the authors actually agree with all of our caveats (detailed in the discussion section of the paper) concerning the use of accelerated corneal cross-linking (CXL) protocols in clinical practice. And we do indeed agree that revisions of CXL parameters should be implemented cautiously, with safety uppermost in mind.
However, it is unfortunate that the authors of the letter were so unsuccessful in their literature search. They state that they could find only a lone modified accelerated CXL study, one that dealt with the treatment of acanthamoeba keratitis. But there are indeed other, more relevant publications. In the realm of modified-accelerated protocols using similar energy settings as those in our study, there is a 1-year follow-up report using 4 minutes and 20 seconds of irradiation at 30 mW/cm 2 , which translates into 7.5 J/cm 2 , a 40% higher total energy dose than that of the Dresden protocol. Moreover, Mazzotta and associates have published results of a novel pulsed-light accelerated CXL technique using ultraviolet A (UVA) at 30 mW/cm 2 for 4 minutes, also corresponding to an increased total surface energy dose (7.2 J/cm 2 ).
Further, we take the liberty to refer a peer-reviewed poster (Gore D, Nicholae M, Kopsachilis N, et al: Rapid corneal collagen cross-linking for progressive corneal ectasia: 12-month results) shown at the Congress of the European Society of Cataract and Refractive Surgeons in September 2014 in London. The poster emanates from Moorfields Eye Hospital, the same institution that 4 of the letter authors represent. It reports on UVA exposure at 30 mW/cm 2 for 4 minutes, also corresponding to a total surface energy dose of 7.2 J/cm 2 .