PubMed · 15130620
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David Lieberman, Jonathan Grierson. 2004. Fourier analysis.. https://doi.org/10.1016/j.jcrs.2004.04.009
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PURPOSE: The aim of this study was to assess astigmatism magnitude and axis changes based on the dioptric power matrix in low to moderate levels of myopia and astigmatism treated with LASEK. PATIENTS AND METHODS: This retrospective analysis included 54 myopic eyes treated with LASEK with a minimum follow-up of 12 months. An epithelial flap was created by 25-45 s of 20% alcohol exposure. The corneal surface was ablated using two different excimer lasers and nomogram adjustment. The flap was repositioned and a bandage applied to the contact lens. Main outcome measures were manifest refraction as calculated with the dioptric power matrix, UCVA, BSVCA, and retreatment rate. RESULTS: Mean manifest refraction is shown in table 2 (Tabelle 2). UCVAs of 20/20 or better were found in 33% of eyes at 1 week and in more than 53% at 3 months to 1 year. The safety index remained > or =0.98 after postoperative week 4. The efficacy index varied between 0.91 and 0.98 after 1 month. CONCLUSION: LASEK for correction of low to moderate myopia and astigmatism seems to be a safe, effective, and stable option.
One approach to aberration compensation of an imaging system is to introduce a suitable phase mask at the aperture plane of an imaging system. We utilize this principle for the compensation of astigmatism. A suitable polarization mask used on the aperture plane together with a polarizer-retarder combination at the input of the imaging system provides the compensating polarization-induced phase steps at different quadrants of the apertures masked by different polarizers. The aberrant phase can be considerably compensated by the proper choice of a polarization mask and suitable selection of the polarization parameters involved. The results presented here bear out our theoretical expectation.
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