Factor Analysis of Unintended Initial Dissection of the Posterior Plane

Study Overview
=================
Brief Summary
-----------------
To explore the potential factors for unintended initial dissection of the posterior plane in a large sample retrospective analysis and surgeons of different levels.

Detailed Description
-----------------
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.

Official Title
-----------------
Identification of Factors Related to Unintended Initial Dissection of the Posterior Plane in Small Incision Lenticule Extraction Cases by Three Different Surgeons

Conditions
-----------------
Myopia, Small-incision Lenticule Extraction (SMILE) Surgery

Intervention / Treatment
-----------------
* Procedure: Small incision lenticule extraction


Participation Criteria
=================
Eligibility Criteria
-----------------
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.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Eyes with SMILE surgeries<br>Eyes with SMILE surgeries which were performed by three surgeons with different experiences. | Procedure: Small incision lenticule extraction<br>* Small incision lenticule extraction surgeries performed by two Refractive surgery experts (Refractive surgery expert 1: YYF, Associate Professor with 10 years of experience as a refractive surgeon; Refractive surgery expert 2: GF, Associate Professor with 5 years of experience as a refractive surgeon) and a Attending ophthalmologist (WNY, Attending ophthalmologist with 1 year of experience as a refractive surgeon).<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The number of patients with unintended initial dissection of the posterior plane in the SMILE surgeries | The number of patients with unintended initial dissection of the posterior plane were observed during the SMILE surgeries. | Day 0 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The impact of spherical equivalent on the unintended initial dissection of the posterior plane (UIDPP) in SMILE surgeries | The spherical equivalent of eyes with UIDPP and eyes without UIDPP were analyzed, and statistical analysis was observed to investigate the impact of spherical equivalent on the UIDPP in SMILE surgeries. | Day 0 | 
| The impact of peripheral corneal incision angle on the unintended initial dissection of the posterior plane (UIDPP) in SMILE surgeries | The peripheral corneal incision angle of eyes with UIDPP and eyes without UIDPP were analyzed, and statistical analysis was observed to investigate the impact of peripheral corneal incision angle on the UIDPP in SMILE surgeries. | Day 0 | 
| The impact of peripheral lens thickness on the unintended initial dissection | The peripheral lens thickness of eyes with UIDPP and eyes without UIDPP were analyzed, and statistical analysis was observed to investigate the impact of peripheral corneal incision angle on the UIDPP in SMILE surgeries. | Day 0 | 
| The impact of lens diameter on the unintended initial dissection | The lens diameter of eyes with UIDPP and eyes without UIDPP were analyzed, and statistical analysis was observed to investigate the impact of lens diameter on the UIDPP in SMILE surgeries. | Day 0 | 
| The impact of central corneal thickness on the unintended initial dissection | The central corneal thickness of eyes with UIDPP and eyes without UIDPP were analyzed, and statistical analysis was observed to investigate the impact of central corneal thickness on the UIDPP in SMILE surgeries. | Day 0 | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
femtosecond laser, small-incision lenticule extraction (SMILE), unintended initial dissection of the posterior plane