Purpose: To compare corneal densitometry values after Femtosecond Laser-Assisted In Situ Keratomileusis (Fs-LASIK) and Small Incision Lenticule Extraction (SMILE) using Scheimpflug Imaging.
Methods: Our retrospective clinical trial included a total of 146 eyes where 57 eyes underwent Fs-LASIK and 89 eyes underwent SMILE. Examinations with a Pentacam Scheimpflug device (Oculus, Wetzlar, Germany) were performed before surgery, 1 week, 1 month, 3 months, 6 months, and 1 year after surgery. Detailed data of all four concentric optical zones were acquired - central 0-2 mm, 2-6 mm, 6-10 mm and 10-12 mm. The cornea was divided into anterior 120 µm, middle and posterior 60 µm sections. Values were analyzed during follow-up comparing Fs-LASIK and SMILE.
Results: No statistically significant differences in corneal density were detected. The central 0-2 mm anterior area demonstrated a mean 1-year value of 17.99 grayscale units (GSU) ± 0.89 (range 16.60-19.50) after Fs-LASIK versus 17.96 GSU ± 0.98 (range 16.40-20.00) after SMILE. Three months after surgery there was a slight temporary density increase in the 6-10 mm anterior annulus in the LASIK group - 22.19 (SD = 3.99, range: 15.60-30.50) compared to SMILE - 20.39 (SD = 3.79, range 14.70-36.30).
Conclusion: There were no statistically significant short or long-term differences in postoperative corneal densitometry after LASIK and SMILE, demonstrating SMILE is not inferior in this regard. Known delayed visual acuity recovery after SMILE in relation to LASIK could not be correlated with changes in corneal density.
Keywords: Corneal densitometry; LASIK; SMILE.