We read the article by Borderie and associates with great interest. We commend the authors’ effort and find their results consistent with available evidence. While it is interesting to know that eyes undergoing anterior lamellar keratoplasty (ALK) had a lower incidence of rejection episodes and irreversible rejection compared to the penetrating keratoplasty (PK) group, could the authors kindly throw some light on the following questions that came up in our discussion?

In Figure 1, the authors highlight that only 77 patients in the ALK group completed follow-up at 36 months. In Figure 2, however, it is stated that the cumulative incidence of reversible and irreversible rejection episodes of 149 ALK patients with a 36-months-postoperative time period was 0% and 10%, respectively. It is unclear, however, how these figures were calculated given that only 77 patients were followed up to 36 months.

In addition, in terms of graft survival, it would be helpful if the authors would provide information on the remaining 72 patients of the ALK group, for whom no follow-up data are provided. That is, how many patients were lost to follow-up and what were the reasons for this? If even 1 or 2 more patients in the ALK group had graft failure, this would have a significant effect on the overall graft survival, particularly in comparison to the PK group. In addition, similar data for the 28 patients who had PK would be informative.

Essentially, graft failure and/or rejection episodes in the patients who were lost to follow-up could have a significant bearing on the outcomes reported, and this needs clarification.