The Long-term observation of the quick contrast sensitivity and its influencing factors after SMILE.

PURPOSE: This study investigates the long-term impact of Small Incision Lenticule Extraction (SMILE) on quantitative contrast sensitivity (qCSF) and its determinants.

MATERIALS AND

METHODS

The research involved 80 eyes (mean spherical equivalent -6.10±1.95 D), including 40 highly myopic eyes. Seven years post-surgery, assessments included manifest refraction, axial length, corneal topography, and qCSF. Tangential curvature difference maps measured decentration and effective optical zone (EOZ). Statistical analysis explored correlations between qCSF metrics and ocular parameters.

RESULTS

SMILE surgeries were uncomplicated. Safety and efficacy indices were 0.89±0.21 and 1.11±0.11, respectively. Significant correlations existed between cylindrical refraction (CR), residual CR, and qCSF [CR: AULCSF (r=0.061, p=0.010), CSF acuity (r=1.717, p=0.010); residual CR: AULCSF (r=-0.174, p=0.004), CSF acuity (r=-6.271, p<0.001)]. Subgroup analysis showed enhanced contrast sensitivity with lower ablation. Higher initial CR and lower residual CR correlated with superior qCSF. Long-term decentration negatively impacted qCSF in high myopia. EOZ in low-middle myopia differed significantly in qCSF metrics.

CONCLUSION

SMILE demonstrated excellent 7-year outcomes. In the low-to-moderate myopia group, all eyes (100 %) achieved UDVA of 20/25 or better, and postoperative astigmatism was within ±0.50 D. In the high myopia group, 72.5 % achieved UDVA ≥20/25. Greater preservation of corneal thickness was associated with better postoperative contrast sensitivity and visual quality, whereas residual astigmatism and minor decentration were linked to slightly reduced long-term outcomes.