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Michelle Langeslag, St. Schmickler, Roland Pohl, Kristen Featherstone, Patricia A Piers; Comparing in vivo and in vitro optical characteristics of diffractive multifocal IOLs with different add powers. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3755.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study is to compare various optical performance criteria from in vivo and in vitro measurements of diffractive multifocal intraocular lenses (IOLs) having different magnitudes of add power.
Diffractive multifocal IOLs with add powers of 2.75, 3.25 and 4.0D were tested on an optical bench, as well as in a clinical setting. In vitro testing included: best focus and through-focus Modulation Transfer Function (MTF) measurements on an optical bench in an eye model that reproduces the spherical and chromatic aberration of an average pseudophakic eye, using different aperture sizes and white light, also simulated halo images were composed. Additionally, using computer-based individualized model eyes, defocus curves were simulated both for visual acuity and contrast sensitivity. In vivo testing included a prospective, multicenter, open-label study of IOLs having an add power of 2.75 and 3.25D at six European investigative sites. All patients signed informed consent. For both IOLs, 15 patients were enrolled and bilaterally implanted. All completed the 3-month follow-up study visit. Amongst others, the distance-corrected near visual acuity (DCNVA), best-corrected distance vision and depth of focus were tested. As a representative for the 4.0D add power IOLs, the registration study results for the optical parent, having a similar optical profile, were used to compare optical measurements to clinical performance.
For both in vivo and in vitro results, the absolute best-focus performance for near and far distances was independent of add power. The locations of the best-focus near peak changed with a change in add power. Halo images showed that IOLs with lower add power produce smaller halos. Simulated visual acuity through-focus graphs were constructed for the three different add powers (Figure 1). The uncorrected monocular defocus curves obtained from in vivo measurements are presented in Figure 2. Best far and near visual acuity is 0.1logMar or higher for all cases. Intermediate vision increases with a lower add power.
Lowering the add power of diffractive multifocal IOLs has no effect on in-focus near and far vision, both in vivo and in vitro. Intermediate visual acuity increases when add power is reduced. In vitro simulated through-focus curves are representative for in vivo behavior.
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