To explore the potential factors for unintended initial dissection of the posterior plane in a large sample retrospective analysis and surgeons of different levels.

Myopia is the most common eye disease in the world. Femtosecond laser small incision lens extraction (SMILE) has increasingly become the first choice in refractive surgery due to its greater biomechanical stability, less impact on the tear film and other advantages. However, because SMILE surgery is more challenging than flap-based corneal ablative surgery, young surgeons sometimes dissect the lenticule posterior plane first in clinical practice, which will make it more difficult to extract the lenticule or even cause the retained lenticule. The purpose of this study aims to explore the potential risk factors for unintended initial dissection of the posterior plane in large samples and surgeons of different surgical volumes and different surgical habits (different angles of peripheral corneal incision) in multiple scenarios.

Inclusion Criteria:

• A condition in which the spherical equivalent refractive error of an eye is ≤ -0.50 D when ocular accommodation is relaxed;
• Age ≥18 years;
• Spherical equivalent (SE) ≥ -10.0D;
• Corrected distance visual acuity (CDVA) ≥ 16/20;
• Stable myopia for at least 2 years;
• No contact lenses wearing for at least 2 weeks.

Exclusion Criteria:

• The presence or history of eye conditions other than myopia and astigmatism, such as keratoconus or external eye injury;
• A history of eye surgery;
• The presence or history of systemic diseases.

Patients from clinics in ophthalmic center of the second Affiliated Hospital of Nanchang University