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A. Yasuda, D.R. Hamilton; Effect of Spherical Aberration and Pupil Aperture on Correlation Between Wavefront and Manifest Refraction . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4652.
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Purpose:To investigate the effect of pupil size and spherical aberration(SA) on the wavefront refraction(WRSE) in pre– and post–operative eyes, and determine which pupil size and SA weighting yields the smallest WRSE/Manifest refraction (MRSE) difference. Methods:A retrospective chart review of 74 eyes of 42 patients who underwent wavefront guided LASIK for myopic astigmatism using the Custom Cornea aberrometer and LADARVision 4000 excimer laser (Alcon Laboratories, Ft. Worth, TX) was done. Pre– and post–operative MRSE, WRSE and root mean square (RMS) values for SA measured across 3.0 mm, 4.5mm and 6.0mm were recorded for each eye. The correlations between the WRSE/MRSE difference and each pupil size and SA were analyzed pre– and post–operatively. Results: A positive correlation existed between pupil size and the WRSE/MRSE difference, a correlation which was stronger postoperatively (p<0.001) than preoperatively (p=0.85). The smallest WRSE/MRSE differences were obtained with a 2.8mm pupil preoperatively and a 4.9mm pupil postoperatively. WRSE showed a hyperopic shift in a larger aperture than these pupil sizes, and showed a myopic shift in a smaller pupil in both the pre– and post–operative eyes. A significant positive correlations existed between SA and the WRSE/MRSE differences preoperatively (r=0.33, p<0.001) and postoperatively (r=0.30, p<0.001). A higher RMS value of SA led to a larger hyperopic shift of WRSE. Conclusions:The WRSE showed a hyperopic shift with larger pupil apertures and larger RMS values of SA, especially in postoperative eyes. Custom nomograms for wavefront–guided LASIK may need to include pupil size and spherical aberration adjustments to improve outcomes.
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