Dialing Down The Dose: Exploring Femtosecond Laser-Induced Optical Breakdown Levels And Their Impact On Visual Outcomes
Published 2025 - 43rd Congress of the ESCRS
Reference: FP14.01 | Type: Free paper | DOI: 10.82333/6ffr-1d46
Authors: Claudio Orlich* 1 , Damien Goldberg 2 , Leonard Seibold 3 , Brian Flowers 4 , Paul Singh 5 , Sydney Tyson 6 , Mohammed ElMallah 7 , Elysia Ison 8 , Med Harbin 8 , Malik Kahook 9
1Anterior Segment,Clinica 20/20,San Jose,Costa Rica, 2Anterior Segment,Wolstan and Goldberg Eye Associates,Torrance,United States, 3Glaucoma,University of Colorado Anschutz Medical Campus,Aurora, CO,United States, 4Glaucoma, Ophthalmology Associates ,Fort Worth,United States, 5Glaucoma,Eye Surgery Wisconsin ,Kenosha,United States, 6Anterior Segment,Eye Associates & SurgiCenter of Vineland,Philadelphia,United States, 7Glaucoma,Ocala Eye,Ocala,United States, 8Medical Affairs,New World Medical,Rancho Cucamonga,United States, 9Glaucoma,Rocky Mountain Lions Eye Institute,Aurora, CO,United States
Purpose
This study examined how variations in femtosecond laser dose (mJ/cm²) and pulse energy (nJ) affect early and one-month postoperative uncorrected distance visual acuity (UDVA). The dataset comprised 115 eyes treated over a learning period, allowing analysis of dose/energy thresholds for potential benefits. We specifically investigated whether “low” settings (below certain cutoffs) consistently provide superior vision at postoperative day one (POD1), and whether these advantages persist or diminish by one month.
Setting
Eye Clinic Svjetlost, Zagreb, Croatia
Methods
Laser settings and clinical outcomes were retrospectively analyzed. Dose thresholds of approximately 333–666 mJ/cm² were compared against higher doses, and pulse energy cutoffs around 78–85 nJ were similarly evaluated. Mean UDVA outcomes at POD1 and one month were assessed using t-tests, F-tests, chi-square, and effect size estimates (Cohen’s d). Dose and pulse energy were examined for correlation with treatment date to account for any learning-curve effects.
Results
At POD1, lower-dose treatments (e.g., below 555 mJ/cm²) and lower pulse energies (e.g., below 78 nJ) correlated with significantly better UDVA, as confirmed by multiple statistical tests (p < 0.05). Differences were especially pronounced for certain intermediate dose ranges, with negative effect sizes indicating a clear advantage for “low” settings. By one month, most UDVA disparities disappeared, although doses below ~380 mJ/cm² continued to show modestly better results. Dose showed a stronger and more consistent impact than pulse energy.
Conclusions
Lower femtosecond laser doses and pulse energies can enhance early postoperative UDVA, most notably at POD1. The benefit diminishes by one month, suggesting the primary advantage is in short-term visual recovery. Dose exerted the most robust effect, though both parameters trended favorably when reduced. Because dose and pulse energy correlated with treatment date, learning-curve factors cannot be excluded. Overall, optimizing laser parameters—particularly lowering the total dose—appears beneficial for early visual outcomes.