In their retrospective review published in the January 2020 issue, Chan et al1 assessed safety and efficacy outcomes after re-treatment for residual refractive errors in eyes with prior laser in situ keratomileusis (LASIK). However, the lack of some details regarding the significant contributing factors that may affect the final refractive outcomes in this series are not elucidated.
There are no data regarding selected ablation profiles in performing re-treatments and the mean optical zone of enhancement in the myopia and hyperopia groups. Of note, we may consider some undercorrection in the cases of enhancement procedures with topography-guided or wavefront-guided profiles. Moreover, the duration of applying mitomycin C in the eyes that underwent surface ablation is essential to account for when evaluating safety and refractive outcomes.2,3
One of the major factors guiding selection of the enhancement technique is the thickness of the created LASIK flap and residual stromal bed in primary procedures, which are not mentioned by the authors.4 Furthermore, there are serious concerns about the criteria in preoperative planning to consider eyes for performing re-treatment in terms of the amount of refractive errors.
In the patients and methods section, the authors mentioned that they included manifest refraction before re-treatment; however, they did not mention exactly how they assessed the end-point refraction or if they considered dry or cycloplegic refraction in the presence of significant discrepancy between them. That would especially be of importance in eyes with residual hyperopia.
The significance of these factors requires further details to assess the refractive outcomes. Thus, the results may be confounded due to the lack of data regarding the aforementioned parameters in the study.
Because the refractive regression is an evolving process, epithelial map patterns could be considered as a contributing factor in determining the approach for enhancement.5
Hossein Aghaei, MD
Acieh Es'haghi, MD
Editor's Note: The authors declined to comment on this letter.
- Chan C, Lawless M, Sutton G, Hodge C. Re-treatment in LASIK: to flap lift or perform surface ablation. J Refract Surg. 2020;36(1):6–11. doi:10.3928/1081597X-20191211-02 [CrossRef]
- Randleman JB, White AJ Jr, Lynn MJ, Hu MH, Stulting RD. Incidence, outcomes, and risk factors for retreatment after wavefront-optimized ablations with PRK and LASIK. J Refract Surg. 2009;25(3):273–276. doi:10.3928/1081597X-20090301-06 [CrossRef]
- Teus MA, de Benito-Llopis L. Laser-assisted subepithelial keratectomy with MMC to treat post-LASIK myopic regression. J Cataract Refract Surg. 2007;33(10):1674–1675. doi:10.1016/j. jcrs.2007.06.030 [CrossRef]
- Schallhorn SC, Venter JA, Hannan SJ, Hettinger KA, Teenan D. Flap lift and photorefractive keratectomy enhancements after primary laser in situ keratomileusis using a wavefront-guided ablation profile: refractive and visual outcomes. J Cataract Refract Surg. 2015;41(11):2501–2512. doi:10.1016/j.jcrs.2015.05.031 [CrossRef]
- Kanellopoulos AJ, Asimellis G. Longitudinal postoperative LASIK epithelial thickness profile changes in correlation with degree of myopia correction. J Refract Surg. 2014;30(3):166–171.