Comparing the Existing Myopic Keratorefractive Lenticule Extraction (KLEx) Platforms: A Narrative Review [Response to Letter]

Dear editor

We commend Drs. Fedchuk, Grossenbacher, and Leccisotti for their thoughtful feedback regarding our article, “Comparing the Existing Myopic Keratorefractive Lenticule Extraction (KLEx) Platforms: A Narrative Review.”¹ We sincerely appreciate their recognition of our efforts to synthesize both early and long-term outcomes across emerging KLEx platforms.

In our review, we acknowledged the variability in study methodologies, outcome measures, reporting standards, and patient demographics, which represent a significant limitation of our analysis. This made it challenging to accurately and fairly compare the current KLEx platforms.

Our colleagues raise an important methodological point regarding the omission of explicit preoperative corrected distance visual acuity (CDVA) values when reporting postoperative uncorrected distance visual acuity (UDVA) as a measure of efficacy. We agree that preoperative CDVA provides valuable context when interpreting postoperative UDVA outcomes and that reporting it enhances clarity regarding visual efficacy. However, we would like to clarify that our review did, in fact, assess efficacy relative to preoperative CDVA, as stated in the text (page 2196): “Efficacy was assessed by the change in UDVA postoperatively compared to preoperative CDVA.”¹ Although the percentage of eyes experiencing a change in Snellen CDVA was presented in Table 4, this was included as a descriptive measure of safety. Efficacy data were further discussed in the text to provide a balanced interpretation of each platform’s visual outcomes.

Across the included studies, efficacy data were presented heterogeneously. Most studies expressed efficacy as the percentage of eyes with postoperative UDVA equal to or better than preoperative CDVA, reflected in the Snellen line difference reported in our review. In contrast, the study by Leccisotti et al² using the CLEAR platform reported efficacy as postoperative UDVA at 10 months (page 1250).² However, the efficacy index, defined as postoperative UDVA divided by preoperative CDVA, was also provided. The reported efficacy index was 1.00, indicating no change in Snellen lines, and was included in our analysis to provide a comprehensive and comparative assessment across platforms. Similarly, the studies by Leccisotti et al³ and Bteich et al⁴ did not report overall efficacy in terms of percentage of eyes with Snellen line changes or the ratio of postoperative UDVA to preoperative CDVA.

Regarding our colleagues’ reference to the CLEAR platform studies by Leccisotti et al³ and Bteich et al,⁴ our discussion of age as a contributing factor to the difference in postoperative UDVA was intended as a contextual observation rather than a definitive causal attribution. Our mention of age as a potential contributor to the discrepancy in postoperative UDVA outcomes was not meant to exclude other factors, such as baseline CDVA, but rather to illustrate that several demographic and methodological variables likely influence postoperative efficacy. Both age distribution and preoperative CDVA can affect postoperative UDVA outcomes, and given the variability in sample characteristics and study design across the KLEx literature, we included age as one of several plausible explanatory factors. Nonetheless, we agree with our colleagues that we could have elaborated to include the percentage of eyes achieving a postoperative UDVA of 20/20 relative to preoperative CDVA to further clarify the interpretation of CLEAR outcomes.

We respect our colleagues’ intent to clarify their results, as reflected in our study, and are grateful for their constructive feedback. We hope it can be acknowledged that there were methodological and reporting differences among the included studies. Our objective was to present the data as comparably as possible while acknowledging these inherent limitations. This narrative review aimed to provide an introductory overview of current KLEx procedures and to show that all platforms demonstrate similar overall efficacy. We once again thank our colleagues for their thoughtful engagement and valuable contributions to this discussion.