Enhancing Visual Quality In Smile Pro Surgery: Impact Of Pulse Energy And Spot Distance On Postoperative Outcomes

To evaluate the effects of femtosecond laser pulse energy and spot distance on postoperative visual quality, aberration, and refractive stability in Small Incision Lenticule Extraction (SMILE) Pro surgery.

Single center, Retrospective, Comparative study

Study included 805 eyes of 413 patients undergoing refractive surgery with VisuMax 800.Track distance was fixed at 3.0 µm with spot distance stratified as 3.7 µm (n=243), 4.0 µm (n=286) and 4.3 µm (n=276). Pulse energy were 85 nJ (n=182), 100 nJ (n=205), 115 nJ (n=223), and 130 nJ (n=195), forming 12 subgroups. Outcomes included objective scatter index, spherical aberration, coma (horizontal/vertical),UDVA, in logMAR, and refractive parameters (spherical/cylindrical powers), assessed at 1 and 3 months postoperatively. Statistical analyses employed one-way ANOVA for initial comparisons, general linear model for inter-group differences, and linear mixed-effects models for temporal changes and interactions (energy-spot distance or time-energy)

OSI increased with higher pulse energy across all spot distances and timepoints, with the lowest values at 85 nJ (OSI: 0.611±0.249) compared to higher energies(1.008±0.698).OSI decreased over time, but no consistent energy-spot distance interaction was observed. SA also showed energy-dependent increases, with values at 3 months ranging from 0.168±0.150 to 0.270±0.238 µm, and spot distance effects varied by energy without significance.Coma aberration exhibited no significant differences by energy or spot distance. UDVA was excellent and stable (>1.1 decimal equivalent on average at 3 months; p>0.05 across groups). Refractive outcomes were stable through 3 months follow period in all groups.

Lower pulse energy (85 nJ) is associated with reduced postoperative OSI and SA in SMILE Pro, with spot distance showing variable but non-significant modulating effects. These findings suggest potential benefits of low-energy settings for visual quality, though further studies are needed to confirm optimal spacing and long-term outcomes.