Comparison of dynamic changes in the effective optical zone in Low-Moderate and high myopia with a novel method and...

To investigate changes in the Effective Optical Zone (EOZ) using a novel method, evaluate visual outcomes within six months following Small Incision Lenticule Extraction (SMILE), and analyze the changes in postoperative visual outcomes. This retrospective study evaluated patients who underwent SMILE and were assessed during a 6-month follow-up. 95 eyes were divided into two groups: low to moderate myopia (LM, SE ranging from - 0.50D to -6.00D) and high myopia (HM, SE ranging from - 6.00D to -9.00D). Postoperative EOZ was automatically distinguished by custom software on the tangential curvature difference map. Higher-order aberrations (HOAs), Q-values, and Strehl ratios (SR) were analyzed for the central 4 mm and 6 mm corneal zones. Changes in EOZ (△-OZ) and other parameters were monitored and compared between the two groups. The EOZ was significantly larger in LM group than in HM group (25.45 ± 2.19 vs. 23.88 ± 1.53mm²), and the changes in vertical diameter exceeded those in horizontal diameter in both groups (P < 0.01). All patients showed increased HOAs, spherical aberration (SA), and coma compared to preoperative values (all P < 0.01), with higher values in HM group. The changes in Q-value, HOAs, and SA were positively correlated with △-OZ (r = 0.640, r = 0.534, r = 0.680, all P < 0.01). No significant differences in SR, visual acuity, or refractive error between the two groups. EOZ stabilized by 3 months postoperatively while Visual Outcomes at 1 month. Following SMILE surgery, the EOZ decreased and stabilized at around 3 months. Higher preoperative myopia was associated with increased corneal remodeling, larger HOA changes, and greater EOZ reduction, without significantly affecting visual outcomes.