Effect Of Total Laser Fluence On Early And Mid-Term Visual And Optical Quality Outcomes After Lenticule Extraction With The Schwind Atos: A Single-Centre Study

To evaluate the effect of total laser fluence on early and mid-term visual outcomes after

keratorefractive lenticule extraction (KLEx) performed with a femtosecond laser.

Single-surgeon, single-centre refractive surgery clinic. 

Retrospective comparative cohort analysis of prospectively collected data.

This retrospective comparative case series included 112 eyes of 112 patients. Eyes were stratified

into four quartiles (Q1–Q4, n=28 each) based on total fluence (range 290–767 mJ/cm²). Outcomes

included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest

spherical equivalent (SEQ), and higher-order aberrations (HOAs) measured by corneal and ocular

wavefront at 4- and 6-mm. Assessments were performed at postoperative day 1 (POD1) and month 6 

(POM6). Statistical analyses used Kruskal–Wallis and Mann–Whitney U tests with Holm step-down

correction.

At POD1, lower fluence groups showed faster UDVA recovery (Q1 −0.11 ± 0.07 vs Q4 −0.01 ± 0.10

logMAR), but these differences were not significant after Holm correction. By POM6, UDVA was

excellent across all quartiles. CDVA line gains were significantly more frequent in Q1 and Q2 (79%

and 54% gained ≥1 line) compared with Q3 and Q4 (7% each, Holm-adjusted p<0.005). Predictability

remained high, with 82–93% of eyes within ±0.50 D at 6 months. HOA induction was slightly greater

with higher fluence at POD1 but converged by POM6, except spherical aberration at 6 mm, differed

significantly (p=0.006)

Lower total fluence was associated with non-significant trends toward faster recovery and greater

mid-term CDVA gains, while refractive accuracy and safety were not compromised. Fluence

optimization may enhance early visual quality without sacrificing predictability.