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G Scorcia, V Scorcia, F Scarinci, M Fratto, GM Vergati; Myopic Over Correction and Final Hyperopic Ablation to Reduce Corneal Spherical Aberration in High Myopia . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2056.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To reduce the spherical aberration introduced by laser epithelial keratomileusis (LASEK) in high myopia Methods: LASEK was performed with NIDEK EC 5000 laser with the aim to correct myopia errors from 6.00 to 14.00 diopters on 100 eyes (127 patients). All eyes were divided into two randomised groups: GROUP I: lasek was performed in 50 eyes of 62 patients on by technique of multizone ablation pattern (the zone were between 4.5mm and 6.5mm). GROUP II: 50 eyes of 65 patients received the same multizone ablation pattern with myopic over correction and hyperopic final ablation. Pre surgical and post surgical corneal topography of all patients with CSO topography were obtained. Post surgical corneal asphericity (E), longitudinal spherical ablation (LSA), curvature standard deviation (SD) and surface asymmetry index (SAI) were examinated in lasek-treated eyes. Results: Group I: the mean corneal asphericity value was -0.82, the mean LSA value was 1.20 D, mean curvature standard deviation was 1.30 D and 0.60 D the mean SAI. Group II: the mean E value was -0.21, the mean LSA value was 0.35; the mean SD was 0.56 and 0.25 the mean SAI Conclusion: Current lasek ablations introduce spherical aberration into the eye. The theoretical ideal ablation pattern requires additional flattering of the ablation periphery to avoid the introduction of spherical aberration. Hyperopic final ablation after myopic over correction may reduce post surgical regression and improve visual performance
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