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Jeff Grigsby, Kathy Vasquez, Michael Tschoepe, Thomas Walters, Billy Cook, Robert Sheets, Dennis Neely; The effect of high order aberrations on the accuracy of wavefront ablations using LASEK on high myopes. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3139.
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© ARVO (1962-2015); The Authors (2016-present)
LASEK is used to correct myopia, hyperopia, astigmatism and high order aberrations (HOA) such as coma, trefoil and spherical aberration. It is unclear how these pre-operative HOA affect the accuracy of the final refractive result in LASEK. Additionally, Teus,et al., 2007 proposed that LASIK nomograms may overcorrect high myopes receiving LASEK.
A retrospective analysis of 113 eyes of 69 patients who had LASEK performed between 2005-2010 using either a standard or Customvue© ablation was performed. Subjects had at least -6.00 diopters of sphere pre-operatively. The standard ablation group utilizing physician adjustments included 63 eyes averaging -7.49 D sphere and average astigmatism of -1.41 D. The Customvue© ablation group utilizing physician adjustments included 50 eyes averaging -6.56 D sphere and average astigmatism of -0.63D. The use of intra-operative mitomycin C was slightly higher in the standard vs. the Customvue© group (74% vs 54%), but was not different between the pre-operative < 0.1000μ normalized polar Zernicke coefficient (NPZE) and the > 0.1000μ NPZE Customvue© spherical aberration groups. Refractions were performed at 1, 3, 6 and 12 mths post-operatively.
The mean spherical equivalent post-operative refraction was not significantly different between the two groups (standard group mean +0.07 D, std. deviation 0.62 D; Customvue© +0.15 D, 0.58 D). When pre-operative physician adjustments were removed from final Customvue© refractive results, 32% of Customvue LASEK eyes would have had a final result of ≧ ±0.50 D. 23 of the 50 eyes had a pre-operative positive spherical aberration >0.1000μ NPZE. Without a physician adjustment these 23 eyes would have been responsible for 69% of the eyes with post-operative refractions ≥ ±0.50 D. The means were similar between the eyes with pre-operative spherical aberration < 0.1000μ NPZE and those > 0.1000μ NPZE (-0.0136, 0.0413 D), but the variances were significantly different (0.1388 vs. 0.5681 D, p<0.01) indicating more variability post-operatively in the high spherical aberration group.
Standard and Customvue© ablations are effective and accurate in correcting high myopia in LASEK. Pre-operative spherical aberration > 0.1000μ NPZE puts the Customvue© patient at higher risk of enhancement unless adequately compensated with an appropriate physician adjustment.
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