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Z. Bor, M. Brownell, C. Garufis, J. Martiz, A. Chyaet; Elliptical iFS flaps Cause no Astigmatism. Invest. Ophthalmol. Vis. Sci. 2009;50(13):548.
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The 150 kHz femtosecond laser creates flaps in <10 seconds and is capable of creating inverted side cuts (Fig.1) and elliptical flaps having up to 12% longer horizontal axis then the vertical axis. The purpose of this paper is to measure whether elliptical flaps induce astigmatic aberrations.
16 round and 21 elliptical flaps were cut, lifted and replaced without excimer ablation. Aberrations were measured with the Tracey wavefront aberrometer at baseline and 10 weeks post flap creation and the difference in aberrations was calculated.
Double angle plot of astigmatism aberrations (Fig.2) show symmetric angular distribution centered at the origin both for round and elliptical flaps confirming that neither round nor elliptical flaps cause significant astigmatism changes. Aberration changes of 0.1 µm have been shown to not have a measurable effect on visual acuity. The only wavefront change with statistical significance was a hyperopic shift in defocus aberrations of 0.1526±0.28 µm. This hyperopic shift from flap creation is in full agreement with previous studies.
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