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D.F. Warren, L. Thibos, K. Haggerty, L. Wang, D.D. Koch; The Effect of Rotation of Wavefront–Correcting Intraocular Lenses on Image Quality of the Eye . Invest. Ophthalmol. Vis. Sci. 2006;47(13):315.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the tolerance for rotational error of custom intraocular lenses (IOLs) that correct higher and lower order wavefront aberrations. Tolerance defined as the rotational error of the custom IOL that degrades monochromatic image quality (IQ) to that achieved by three comparison IOLs (Case 1: conventional IOL that corrects defocus only, Case 2: toric IOL with perfect alignment that corrects defocus and astigmatism, and Case 3: toric IOL with the same rotation error as the custom IOL).
Corneal aberrations reported by Wang and Koch for 127 eyes (ARVO–05, #703) were reversed in sign to simulate custom IOLs. The IOL wavefront was rotated in 5° steps from 0 to 40° and added to the corneal wavefront to simulate a misaligned IOL. A similar process was used to create the 3 comparison eyes. IQ of each custom–corrected eye, specified by 31 objective metrics1, was compared with each comparison eye to determine a "critical orientation" (CO), defined as the angular misalignment for which IQ in the custom–corrected eye fell to the level of the comparison eye. To maximize IQ in the comparison eyes and minimize the tolerance for misalignment in the custom eyes, 3mm pupils were used.
Tolerance was greatest when custom IOLs were compared with case 1 (mean CO = 28.1° ± 0.46 sem, n=127, corresponding to a 64% loss of IQ relative to the aligned condition). Tolerance was least when the custom IOL was compared with case 2 (mean CO = 15.7° ± 0.64; 43% loss of IQ). Tolerance compared to case 3 was between these two extremes (mean CO = 20.1° ± 0.72; 53% loss of IQ).
Tolerance to misalignment of custom IOLs depends on the comparison standard used. More misalignment error of custom IOLs is required to match the relatively low IQ in eyes corrected with conventional IOLs, compared to well–aligned toric–IOLs. Provided that torional mislalignments of IOLs with current technology do not exceed these tolerances, patients should benefit from custom IOL correction versus current methods of IOL correction. 1. Thibos, et al. Accuracy and precision of objective refraction from wavefront aberrations. J. Vision 2004; 4:329–351.
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