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Huawei Zhao; Optical Ensemble Analysis of the Potential Optical Performance of Aspheric Multifocal Toric IOLs. Invest. Ophthalmol. Vis. Sci. 2013;54(15):839.
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© ARVO (1962-2015); The Authors (2016-present)
Contrast transfer is an important link between pseudophakic visual performance and intraocular lens (IOL) optical performance. This study uses previously validated optical ensemble analysis (OEA, Zhao, Optics Letters) to compute pseudophakic optical performance for acrylic aspheric IOLs with diffractive multifocal anterior or posterior and toric on the accordingly opposite surfaces.
OEA is a Monte Carlo simulation using ZEMAX (ZEMAX Corporation, Bellevue, WA, USA) and a clinically-oriented eye model. MTF values are computed with different astigmatism, asphericity, pupil size, and IOL decentration, tilt and astigmatic orientation error. 600 eyes were simulated for two groups of aspheric multifocal toric IOLs: Group1 [aspheric-toric anterior and 4D-add diffractive multifocal posterior surface; low refractive index (1.47) and chromatic dispersion (Abbe# = 55); full aspheric correction] and Group 2 [aspheric apodized diffractive 3D-add anterior and toric posterior surface; high refractive index (1.55) and chromatic dispersion (Abbe# = 37); partial aspheric correction]. Three cylinder powers were studied for each group (1.5, 2.25 and 3.0 D).
Ocular parameters in Groups1 and 2 agreed well with published clinical data and there were no statistically significant differences between groups (p>0.05). Ocular spherical aberration for Group1 was statistically significantly lower than Group2. Pseudophakic optical performance declined consistently with increasing astigmatic power in each of the two groups. Both IOLs significantly reduced the ocular astigmatism (p<0.05) with no statistically significant difference between the two groups in the astigmatism (p>0.05) and MTFs of far vision (p>0.05). MTFs of near vision for Group1 were statistically significantly better than Group2 (p<0.05).
Acrylic aspheric IOLs with diffractive multifocal anterior and toric posterior or multifocal posterior and toric anterior surfaces reduce refractive astigmatism effectively. Optical performance is better at lower astigmatic corrections. Optical performance of near vision is also better under all light conditions for pseudophakic eyes with low chromatic dispersion IOLs that fully correct ocular spherical aberration.
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