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C. D. Coe, K. S. Bower, J. D. Edwards, D. A. Sediq, B. C. Rimm, S. Molinar, L. Peppers; Photorefractive Keratectomy (PRK) vs. Epi-lasik: Comparing Refractive Outcomes, Monochromatic Aberrations, and Optical Quality. Invest. Ophthalmol. Vis. Sci. 2009;50(13):569.
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To compare the post-operative refractive outcomes, high order aberrations, and optical quality for two refractive surgery procedures.
Prospective, non-randomized clinical trial comparing outcomes from photo-refractive keratectomy (PRK) (n=278) and Epi-lasik (n=165) utilizing an Alcon LADARVision 6000 laser utilizing conventional ablations. Epithelial flaps were generated using the Amadeus II microkeratome with epithelial separator (AMO Surgical, Irvine, California). Post-operative sphero-cylindrical refractions were converted into power vectors consisting of M (mean sphere), J0 (regular astigmatism), and J45 (oblique astigmatism). Monochromatic aberrations up to the 4th order were measured with a Shack-Hartmann wavefront analyzer. Total absolute higher order aberrations (HOA) RMS were also determined. Using Fourier optics and a subject’s wavefront, the area of a 2-D radially averaged MTF (normalized to dl-MTF) was calculated for 2 pupil sizes. Statistical analysis consisted of independent t- tests with an alpha of 0.05.
For M (Epi-lasik: M = +0.12;PRK: M=-0.04), J0 (Epi-lasik: M = +0.07;PRK: M=+0.03), and J45 (Epi-lasik:M=-0.011;PRK: M=+0.013), there were statistically significant differences across procedures. Total absolute HOA RMS did not significantly differ for either a 3mm pupil (Epi-lasik:M=0.098;PRK: M=0.092), or a 6mm pupil (Epi-lasik: M=0.88;PRK: M=0.80). The area underneath a normalized 2D-rMTF was almost identical across procedures and pupil diameter (3mm pupil (p=0.25) 6mm pupil (p=0.84)) and did not significantly differ.
Clinical Trial: :
www.clinicaltrials.gov NCT00413517 and NCT00412568
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