Immediate transepithelial photorefractive keratectomy after suction loss during SMILE.

Abstract

Chung et al. evaluated the surgical outcomes by immediate transepithelial photorefractive keratectomy (T-PRK) after suction loss during SMILE.1 This serves as an important reference because SMILE is likely to become the new benchmark of refractive surgery, and suction loss is one of the serious complications, which still has no standardized treatments.2,3 The authors reported that the overall visual and refractive outcomes were comparable with uneventful eyes at 6 months postoperatively. This offered evidence to support the use of immediate T-PRK in the event of suction loss. Nonetheless, various postoperative visual and refractive outcomes in the T-PRK group, such as uncorrected distant visual acuity, mean absolute cylinder value, and spherical aberrations, were inferior to the uneventful SMILE group. We are of the opinion that immediate T-PRK is not the first choice to manage suction loss for reasons discussed further. Corneal haze secondary to corneal wound healing is a well-documented complication of PRK, especially in high myopic eyes.4 In this article, patients who underwent T-PRK had preoperative spherical error up to −7.12 diopters and were at higher risk of haze formation, which might account for the worse visual outcomes in the T-PRK group. Mitomycin-C (MMC) was widely reported as a prophylactic treatment to prevent haze development after T-PRK. However, the authors did not mention about any intraoperative use of MMC or the incidence of postoperative haze in the T-PRK group. Furthermore, the postoperative outcomes were reported only up to 6 months. However, corneal haze can progress with a deterioration of vision after 6 months. Therefore, it would be desirable to have a longer postoperative follow-up to at least 1 year before one can evaluate the true effect of haze on visual and refractive outcomes. It would be helpful if the authors could clarify whether MMC was used, whether haze was present, and, most importantly, whether the 1-year follow-up data are available or not so that a more comprehensive comparison between the T-PRK and uneventful groups can be appreciated. Previous results of suction loss managed by immediate re-SMILE resulting in significantly worse outcomes compared with uneventful eyes were cited in the discussion, whereas management by T-PRK in this study seemed to yield clinically acceptable outcomes and is preferable. However, in a recent study evaluating a series of 4000 SMILE cases in which suction loss occurred during the same lenticule interface cut as in this study, all were managed by immediate re-SMILE with a thinner cap. The refractive and visual outcomes were unaffected compared with the uneventful group.5 SMILE avoids drawbacks of surface ablation such as postoperative pain, slow recovery, and risk of corneal haze and circumvents the expertise required for T-PRK. Moreover, re-SMILE with a thinner cap does not require a separate excimer laser machine as for T-PRK, which might not be available in all SMILE centers. Re-SMILE with a thinner cap might be preferable in suction loss, whereas T-PRK might serve as an alternative for patients whose corneas were too thin for the former procedure. Further studies seem warranted.