Purpose: To evaluate the differences between the estimated and measured lenticule thickness and relationships in myopic eyes with different refractive errors after small-incision lenticule extraction (SMILE). Methods: This prospective study included a total of 190 eyes (96 patients) with a manifest refraction spherical equivalent (MRSE) of -6.16 ± 1.71 D. The measured lenticule thickness was obtained from digital spectral-domain optical coherence tomography image analysis. The estimated lenticule thickness was obtained from the software program. Comparative statistics and linear regression analyses were performed. Results: At 1 month, the estimated lenticule thickness was 113.68 ± 19.35 µm and the measured lenticule thickness was 96.9 ± 17.5 µm. The difference between the estimated and measured lenticule thickness was 13.63 ± 9.1 µm (p < 0.001) thicker. The difference was lower than the mean data in the moderate myopia group (9.7 ± 6.4 µm) and larger in the high myopia group (12.3 ± 8.8 µm) and the super-high myopia group (17.9 ± 6.9 µm). The discrepancy between the estimated and measured lenticule thickness was significantly dependent on the MRSE (p < 0.001). MRSE only showed significant differences between the three and six-month follow-up visit in the super-high myopic group (p = 0.03). Conclusion: The measured lenticule thickness was thinner than the estimated lenticule thickness for SMILE in most eyes. The higher the refraction, the larger the difference after SMILE surgery. The mismatch between the estimated and measured thickness did not influence the refractive precision and stability of different refractive errors.
Keywords: Lenticule thickness; MRSE; SMILE; predictability; refraction.