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J. Buehren, T. Kohnen; Analysis of Factors Affecting the Change of Higher–Order Aberrations (HOA) After Wavefront–Guided LASIK for Myopia . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4364.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To identify factors that affect the change of higher–order wavefront aberrations (HOA) after wavefront–guided LASIK for myopia. Methods: Sixty myopic eyes of 32 patients were treated with wavefront–guided LASIK (ZyoptixTM version 3.1, Bausch&Lomb) and showed an uncomplicated follow–up of twelve months. The mean preoperative spherical equivalent (SE) was –5.59 ±2.20 diopters (D) (–1.00 to –9.5 D); the mean optical zone (OZ) diameter was 6.70 ±0.68 mm (5.6 to 8.1 mm). Wavefront measurements were performed preoperatively and 12 months after LASIK. Wavefront errors were computed for pupil diameters of 3.5 and 6 mm. Multiple stepwise regression analysis was performed to assess the influence of patient age, SE, sphere, cylinder, OZ size and preoperative HOA (individual terms) on HOA difference. Results: Age, SE, sphere, cylinder and OZ diameter had no significant impact on individual Zernike coefficients at 3,5 mm. At 6 mm, SE and OZ diameter had significant influence only on Z 4,0. Preoperative values of single coefficients had the highest effect on their change. For 6 mm pupils, influence was lowest for Z 3,1 (R²=0,06, b=–0,37) and highest for Z 5,–1 (R²=0,59, b=–1,15). Conclusions: Three groups of factors influenced the change of HOA: The correlation with the magnitude of preoperative HOA values varied among the coefficients and reflected the effect of the wavefront–guided algorithm. SE and OZ diameter affected the induction of spherical aberrations. Third order coma terms were least affected by the factors of the model; their change seems to be a result of randomly acting effects like decentration or flap creation.
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