Feasibility, Safety, and Outcomes With Standard Versus Differential Spot Distance Protocols in Eyes Undergoing SMILE for Myopia and Myopic Astigmatism.

Purpose: To study the feasibility, safety, comparison of intraoperative ease of dissection, and immediate visual outcomes with standard versus differential small incision lenticule extraction (SMILE) spot settings in eyes undergoing bilateral SMILE for myopia or myopic astigmatism.

Methods: One hundred eyes of 50 patients (mean age: 25.4 years) were randomized to receive standard settings (4.5-µm spot and track spacing in cap and lenticule interface) in one eye and differential settings (4.5-µm spot and track spacing in cap interface and 4.2 µm in lenticule interface) in the contralateral eye. Opaque bubble layer (OBL) was graded using a new grading system and a surgeon questionnaire was obtained to grade the ease of dissection (from 0 to 5, with 5 being the easiest) at the end of each surgery. Visual results and optical quality were analyzed at 1 day, 2 weeks, and 3 months postoperatively.

Results: The mean OBL score was significantly lower in the differential group (26.3%) compared to the standard group (35.3%) ( < .01). Consequently, the mean dissection score was significantly higher in the differential group (4.01) compared to the standard group (3.57) ( < .01). The uncorrected distance visual acuity, Objective Scatter Index, modulation transfer function cut-off, and higher order aberrations were comparable with no statistically significant difference between both groups at 1 day, 2 weeks, and 3 months postoperatively ( > .05 for all parameters). No eye in either group had any intraoperative or postoperative complication affecting visual recovery.

Conclusions: Differential spot settings resulted in less intraoperative OBL and easy separability. However, the visual results and optical quality were comparable between groups. .