We read with interest the article by Raiskup et al.1 on corneal collagen crosslinking (CXL) in keratoconus with a follow-up of 10 years. Keratometry (K) values are a very important parameter in evaluating the progression of the condition. We noted that in the abstract (we did not find keratometry data in the results section) the authors indicated that the mean apical K value was 61.5 diopters (D) preoperatively and 55.3 D postoperatively. They did not explain how they measured this apical K value and whether the same device was used preoperatively and postoperatively. It is noteworthy that this value diminished 6.2 D, an amount that is much higher than in other published articles.2–4 The same applies for the reduction in the maximum K (3.64 D) and minimum K (2.0 D).2–4 Moreover, the scale of vertical axis of Figure 1 is not concordant with the shown data; it would be easier to note the change if the scale were between 40.0 D and 65.0 D with intermediate values. In the abstract, the authors indicated that the endothelial cell count (ECC) did not change. However they did not state what percentage of eyes effectively had a cell count available. In addition, they found an increase of approximately 28% in the mean cell density (2214 cells/mm2 to 2831 cells/mm2). Taking in account that the difference between the measurements was approximately 10 years, with an expected total physiologic loss of about 6% for that period, it is a result that is obviously erroneous. As they stated, the explanation could be a different device used; however, another common source of these errors are inaccuracies in entering the values into the database. In addition, specifically for the endothelial cell densities, if the images are not taken in the same location, differences might appear. Retreatment of keratoconic corneas after a first CXL is a topic that is not well defined. The enunciated criterion of a 1.0 D increase in the apical K value in 2 consecutives follow-up visits is not really fully explained. Would that be 1.0 D of increase at each visit, or would it be in total, taking in account the 2 checkup visits? What was the length of time between the visits? We performed a pilot study of 59 eyes with a minimum follow-up of 5 years. In our study, we found a loss of endothelial cells of 3.9% with the same device in the same location, which means about a 0.9% of loss in addition to the physiologic loss. The preoperative mean flat K value in our group of eyes was 46.43 D ± 4.35 (SD) and postoperatively it was 46.04 ± 4.65 D (P = .061). The preoperative mean steep K value in our group of eyes was 51.1 ± 6.24 D and postoperatively it was 50.69 ± 6.29 D (P = .095). Our results are in concordance with those in other published studies.2–4