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JD Lumba, MC Rojas, EE Manche; Analysis of Refractive Vs. Topographic Correction of Astigmatism After LASEK . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2077.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare refractive vs. topographic correction of astigmatism following laser in-situ subepithelial keratomileusis (LASEK). Methods: Retrospective review of 18 eyes of 10 patients that underwent LASEK for myopic astigmatism using the Bausch & Lomb Technolas 217A excimer laser. Manifest refraction and corneal topography using the Keraton topographer were evaluated preoperatively and 3 months postoperatively. Vector analysis was performed for refractive astigmatism correction and topographic astigmatism correction at the corneal plane. Results: Preoperatively, the mean spherical equivalent was -6.68 ± 2.29 diopters (D) (range, -1.63 to -9.25 D), the mean cylinder was +1.50 ±0.72 D (range +0.50 to +2.75), the mean topographic keratometry was 44.47 ±1.64 D (range, 40.97 to 47.31 D), and the mean topographic astigmatism was +1.71 ± 0.64 D (range, 0.04 to 2.88D). Three months postoperatively, the mean spherical equivalent was +0.04 ±0.42D (range, -0.50 to +0.75 D), the mean cylinder was +0.50± 0.48 D (range, 0 to +1.50 D), the mean topographic keratometry was 38.72 ± 1.46 D (range, 36.25 to 41.12 D), and the mean topographic astigmatism was +1.05 ±0.70 D (range, +0.29 to 2.75 D). At 3 months postoperatively, 0.86 D of topographic correction was achieved for every 1 D of spherical equivalent correction at the corneal plane and 0.71 D of topographic astigmatic correction was achieved for every 1D of refractive astigmatic correction. Vector analysis demonstrated a larger mean angle of error for topographic astigmatic correction compared to refractive astigmatic correction (-3.8 vs. - 1.0 degrees), a larger magnitude of error (-0.49 vs. 0.01 D), and a larger difference vector (0.34 vs. 0.24). Conclusion: More refractive correction is achieved than topographic correction after LASEK for myopic astigmatism. Long-term follow-up in a larger series of eyes may further characterize the relationship between refractive and topographic astigmatism correction in eyes treated with LASEK.
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