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First Author: A.Vestergaard DENMARK
Co Author(s): A. Sjølie J. Grauslund J. Hjortdal
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ReLEx flex (flex) and ReLEx smile (smile) are two relatively new corneal refractive procedures, where a stromal lenticule is cut by a femtosecond laser and manually extracted. The purpose of this study was to compare the change in whole-eye and corneal tomography-derived higher-order aberrations (HOA"s) between the two techniques.
Vestergaard A.H.(1,2), Sjølie A.K.(1), Grauslund J.(1), Ivarsen A.(2), Hjortdal J.(2). 1. Department of Ophthalmology, Odense University Hospital, Denmark. 2. Department of Ophthalmology, Aarhus University Hospital, Denmark.
A prospective study of 27 patients treated with flex in one eye, and smile in the other at the Department of Ophthalmology, Aarhus University Hospital. Preoperative spherical equivalent refraction averaged -7.50 D (range -6.00 to -9.75 D) with a maximal astigmatism of -1.75 D in both groups. All patients had stable myopia for at least one year, no other ocular diseases and corrected distance visual acuity ?20/25. A VisuMax® femtosecond laser (Carl Zeiss Meditec, Jena, Germany) was used. Lenticule diameters were the same in both eyes and ranged from 6.00 to 6.50 mm. Flap thickness was 110 to 120 ṁm, and flap/cap diameter ranged from 7.3 to 8.0 mm. Whole-eye wavefront aberrations were measured (WASCA Analyzer, Carl Zeiss Meditec, Jena, Germany) and corneal wavefront aberrations were calculated from the Pentacam tomography data (Oculus, Wetzlar, Germany) for 5-mm pupils and decomposed into Zernike polynomials up to the 8th order (RMS, Root Mean Square, ṁm). For whole-eye aberrations, only measurements of eyes with pupil size 5 mm or less were included (n=23 for flex and n=22 for smile eyes). Patients were examined before and 6 months after surgery.
When comparing mean whole-eye HOAs pre and post-surgery, there was a statistically significant increase in HOAs for both techniques (p<0.001). No difference was found between flex = 0.173 ḟ0.132 and smile = 0.159 ḟ0.115 (p=0.689). Comparing mean corneal derived HOAs pre and post-surgery; In flex eyes, a statistically significant increase of coma = 0.200 ḟ0.150 (p<0.001) and total RMS HOAs = 0.205 ḟ0.152 (p<0.001) were found. A non-significant increase was found for trefoil = 0.028 ḟ0.108 (p=0.195) and a non-significant decrease in HOAs was found for spherical aberration = 0.025 ḟ0.068 (p=0.072). In smile eyes, a statistically significant increase of HOAs were found for coma = 0.160 ḟ0.158 (p<0.001), trefoil = 0.026 ḟ0.066 (p=0.048), and total RMS HOAs = 0.173 ḟ0.136 (p<0.001). A non-significant decrease in HOAs was also found for spherical aberration = 0.013 ḟ0.076 (p=0.364). When comparing mean change in corneal derived HOAs, there was no difference between flex and smile concerning spherical aberration (p=0.522), coma (p=0.207), trefoil (p=0.795), and total RMS HOAs (p=0.276).
The induction of higher-order aberrations after ReLEx flex and ReLEx smile was small and similar when comparing the two techniques. Whole-eye wavefront aberrations, corneal derived coma, trefoil, and total HOAs increased, while corneal derived spherical aberration was unchanged.
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