To evaluate the clinical efficacy and refractive stability of SMILE Xtra compared to SMILE in patients with myopia

Inclusion Criteria:

1. Age between 18 and 50 years.
2. High myopia with a manifest refraction spherical equivalent (MRSE) - 6.00D～-10.00D and refractive changes within ± 0.50D in the past two years;
3. Best corrected distance visual acuity (CDVA) ≥ 20/25.
4. Preoperative refractive status is stable (myopia progression not exceeding 0.50D per year for at least 2 years).
5. Predicted residual stromal thickness (RST) ≥ 250μm after lenticule removal. 6.Soft contact lenses discontinued for at least 1 week, rigid contact lenses for at least 3 weeks, and orthokeratology lenses for at least 3 months.

Exclusion Criteria:

1. The presence of other eye diseases: keratoconus or suspected keratoconus, active keratoconjunctivitis, severe dry eye, glaucoma, retinal diseases such as retinal tears or macular degeneration, etc.,
2. The presence of significant corneal scarring or cataracts affects observation.
3. Systemic diseases such as active systemic inflammation, connective tissue diseases, other conditions that prevent