Factors Influencing Astigmatic Correction Using Small‐Incision Lenticule Extraction: A Systematic Review and Meta‐Analysis

Purpose To systematically review SMILE‐based astigmatism correction and influencing factors. Methods Literature was screened across eight databases. Pre‐ and post‐SMILE cylinder, difference vector (DV), correction index (CI), magnitude of error (ME), angle of error (AE), and index of success (IOS) were compared. Bias was assessed using Cochrane’s Risk of Bias, Quality Assessment of Diagnostic Accuracy Studies, and the Newcastle–Ottawa Scale. Results Elevated ocular residual astigmatism (ORA) resulted in greater postoperative residual astigmatism, accompanied by increased DV and IOS ( p < 0.05), whereas ME, AE, and CI remained unaffected by ORA levels. Postoperative cylinder, DV, ME, AE, CI, and IOS were comparable between eyes ( p > 0.05). Correction outcomes were impacted by ocular rotation, astigmatism characteristics, spherical degree, corneal curvature, and patient age. Conclusions SMILE effectively corrects low, moderate, and high astigmatism, but high ORA patients tend to experience undercorrection. But accuracy requires vector planning.