Refractive Coupling In Lenticule Extraction With Two Different Femtosecond Lasers
Published 2024 - 42nd Congress of the ESCRS
Reference: FP12.12 | Type: Free paper | DOI: 10.82333/xvf9-2t32
Authors: Suphi Taneri* 1 , Soodabeh Darzi 2 , Samuel Arba-Mosquera 2 , Kishore Raj Pradhan 3 , Anika Förster 4 , H. Burkhard Dick 5
1Eye center at St. Francis Hospital,Center of Refractive Surgery Muenster,Muenster,Germany;Ruhr-University Bochum,Bochum,Germany, 2SCHWIND eye-tech solutions,Kleinostheim,Germany, 3Matrika Eye Center,Kathmandu,Nepal, 4Center of Refractive Surgery Muenster,Muenster,Germany, 5Ruhr-University Bochum,Bochum,Germany
Purpose
To evaluate the impact of refractive couplings in myopia and myopic-astigmatism with two different Keratorefractive Lenticule Extraction (KLEx) systems.
Setting
Eye Center at St. Francis Hospital, Münster, Germany, and Matrika Eye Center, Kathmandu, Nepal
Methods
Retrospective evaluation of refractive outcomes with two different lasers studying 2841 eyes undergoing SMILE (Visumax 500, Carl Zeiss Meditec, Germany) and 2528 eyes undergoing SmartSight (ATOS, SCHWIND eye-tech-solutions GmbH, Germany). Coupling effects (derived from the ratio between partial slopes) were determined for sphere and cylinder, and for spherical equivalent, cardinal, and oblique astigmatism separately.
Results
For Visumax, a coupling effect of 8% of cylinder into sphere and a 2% coupling of sphere into cylinder was found. For ATOS, the coupling effect of sphere into cylinder was 1%. A 3% coupling effect of oblique astigmatism into cardinal astigmatism in Visumax, and conversely, a 0.1% coupling effect of defocus into oblique astigmatism in ATOS were found. In cases with no astigmatism plan, sphere had a 2% effect on induced astigmatism in Visumax and 0.6% in ATOS. In high astigmatism plans, sphere had a significant 16% impact on cylinder in Visumax. Additionally, the effect of defocus on cardinal astigmatism was 6% in Visumax and 0.8% on oblique astigmatism in ATOS.
Conclusions
Although statistically significant, coupling effects were consistently low, with magnitudes below 10%, even for astigmatism exceeding 2.5 D. These couplings may be partly attributed to cross-effects of torsional eye movements in addition to the severing of collagen fibers. Coupling values for KLEx were markedly lower than those reported for non-aspheric excimer laser ablations. Our results suggests that surgical results may be refined further by optimizing built-in laser nomograms to mitigate coupling effects.