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M.A. Kroll, J. Narvaez, C. Nelsen, G. Zimmerman, I. Wessels; Comparison of Pseudoaccomodation, Reading Speed, and Contrast Sensitivity between the Aspheric SN60WF Intraocular Lens (IOL) and a Similar Conventional IOL, the SA60AT . Invest. Ophthalmol. Vis. Sci. 2006;47(13):615.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether the SN60WF IOL, created with a posterior aspheric surface to reduce spherical aberration and improve image quality, adversely effects the pseudoaccomodation afforded by a comparable conventional IOL, and assess contrast sensitivity, reading speed, and subjective dysphotopsias between the IOLs.
69 eyes of 44 patients undergoing phacoemulsification were randomly implanted with the aspheric SN60WF IOL and the comparable conventional SA60AT IOL. The two groups were comparable with respect to age, gender, and number of right and left eyes implanted. Each eye was tested one month post–operatively with best corrected distance correction for visual acuity (BCVA) at distance, intermediate (one meter), and near (14 inches). Reading speed and contrast sensitivity were tested with MNRead charts and Pelli Robson charts respectively. Accomodation was measured, and subjective dysphotopsias were evaluated by patient survey. Wavefront analysis of each eye was also performed with the VISX WaveScan system to compare the spherical and higher order aberrations between the two lens designs.
The conventional spherical SA60AT IOL provided significantly better near BCVA when compared to the aspheric design of the SN60WF (P = 0.016). Intermediate BCVA was also better with the conventional spheric IOL, but not to a significant degree (P = 0.07). Distance BCVA was comparable between the two designs. Wavefront analysis confirmed that the SN60WF has significantly less spherical aberration than the SA60AT (P = < 0.001), and also measured significantly more higher order aberrations in the conventional SA60AT (P = 0.002). No significant differences were noted between the two IOL designs with respect to reading speed, contrast sensitivity, or accommodation. Patient survey also revealed no significant difference in subjective dysphotopsias between the two groups.
The aspheric design of the SN60WF, while intended to improve image quality by reducing spherical aberration, may reduce near and intermediate visual acuity, sacrificing the pseudoaccomodation effect provided by conventional spherical IOLs. Further comparison between the two IOL designs revealed no differences with respect to reading speed, contrast sensitivity, accommodation, and subjective dysphotopsias.
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