INTRODUCTION: Corneal ectasia after laser refractive surgery can threaten vision. We aimed to analyze the preoperative clinical, tomographic and biomechanical data of patients submitted to laser vision correction (LVC) – photorefractive keratectomy (PRK) and femtosecond laser-assisted in-situ keratomileusis (FS-LASIK) – for myopia and/or astigmatism and to evaluate their preoperative ectasia risk and their 6-months’ and 24-months’ postoperative ectasia status. METHODS: Retrospective study including patients submitted to FS-LASIK and PRK, between November 2020 and September 2021, that completed at least 6 months of follow-up. Corneal tomography was evaluated with Pentacam HR (Oculus) and corneal biomechanics with Corvis ST (Oculus). The risk of preoperative ectasia was also assessed using the percent tissue altered (PTA) and an artificial intelligence tool (Brain Cornea). At 6 and 24 months postoperatively, we assessed CBI-LVC alongside refractive and tomographic outcomes. RESULTS: A total of 268 eyes from 139 patients were included (group 1 – FS-LASIK: 186; group 2 – PRK: 82) and 210 (FS-LASIK: 142; PRK: 68) completed the follow-up. At 24 months, 3 eyes had a CBI-LVC>0.2 (PRK=2; FS-LASIK=1). No cases of clinically relevant corneal ectasia were identified. In FS-LASIK, K1 and K2 displayed a statistically significant increase between 6 and 24 months, with a positive correlation to preoperative TBI (r(140)=0.263; p=0.008). CONCLUSION: Few eyes displayed a CBI-LVC indicative of post-LVC ectasia. Our refractive screening appears to have been successful, both in safety and stability. The refractive regression in FS-LASIK eyes appears to be higher in eyes with a higher preoperative ectatic risk. Preoperative biomechanics may influence postoperative refractive regression after FS-LASIK.
Bragança et al. (Mon,) studied this question.