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Intraoperative centration during small incision lenticule extraction (SMILE)
John X Wong1, Elizabeth P Wong, Hla M Htoon
1aDepartment of Ophthalmology, Tan Tock Seng Hospital, National Healthcare Group Eye Institute bSingapore Eye Research Institute cTissue Engineering and Stem Cell Group, Singapore Eye Research Institute dSingapore National Eye Centre, Singapore eDepartment of Clinical Sciences, Duke-NUS Graduate Medical School fSchool of Material Science and Engineering and School of Mechanical and Aerospace Engineering, Nanyang Technological University.
Small incision lenticule extraction (SMILE) shows that decentration from the pupil center does not impact visual outcomes. However, greater than 0.6mm decentration from the kappa intercept may compromise vision, suggesting tailored treatment for patients with large kappa intercepts.
Area of Science:
- Ophthalmology
- Refractive Surgery
- Corneal Surgery
Background:
- Small incision lenticule extraction (SMILE) is a popular refractive surgical procedure.
- Intraoperative decentration, the misalignment of the laser ablation from the intended visual axis, can potentially affect surgical outcomes.
- Understanding the impact of decentration relative to both the pupil center and kappa intercept is crucial for optimizing SMILE procedures.
Purpose of the Study:
- To evaluate the degree of intraoperative decentration from the pupil center and kappa intercept during SMILE.
- To assess the impact of this decentration on visual acuity and refractive outcomes following SMILE surgery.
Main Methods:
- A retrospective analysis of 164 eyes that underwent SMILE at the Singapore National Eye Center.
- Intraoperative videos were reviewed to measure decentration from pupil center and kappa intercept.
- Preoperative and 3-month postoperative visual and refractive data were analyzed in relation to the measured decentration.
Main Results:
- Mean decentration from pupil center was 0.13 ± 0.06 mm, and from kappa intercept was 0.47 ± 0.25 mm.
- Decentration from the pupil center did not show a statistically significant association with safety, efficacy, or predictability.
- A trend towards higher efficacy was observed with kappa intercept decentration between 0.4 and 0.6 mm (P=.097), with 85.4% achieving 20/20 unaided distance VA, compared to 57.8% in the ≥0.6 mm group.
Conclusions:
- Intraoperative decentration from the pupil center within the observed range (0.13 mm) does not appear to compromise visual outcomes in SMILE.
- Decentration greater than 0.6 mm from the kappa intercept may lead to compromised visual outcomes.
- Tailoring the lenticule creation 0.4-0.6 mm from the kappa intercept is recommended for patients with a large kappa intercept (>0.6 mm) to potentially improve efficacy.