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Decentration of an IOL increases higher-order aberrations, especially coma.
Dr. Baumeister, Dr. Kasper, and Prof. Kohnen carried out an intra-individual comparison of conventional spheric and aspheric (prolate surface-modified) foldable IOLs to determine the effect of decentration on higher-order aberrations.
The AR40e IOL (Advanced Medical Optics Inc., Santa Ana, CA) was implanted in one eye and the Tecnis Z9000 aspheric IOL (AMO) was implanted in the fellow eye.
Three months after the IOLs were implanted following phacoemulsification, optic decentration was measured using Scheimpflug photography (EAS-1000, Nidek, Fremont, CA), and the wavefront aberrations were measured using a Hartmann-Shack sensor (Zywave, Bausch & Lomb, Rochester, NY), he explained. Dr. Baumeister is lecturer in ophthalmology, Department of Ophthalmology, Johann Wolfgang Goethe- University, Frankfurt am Main, Germany.
"Clinically, there was excellent centration of the IOLs in our patients with no significant intra-individual differences. We found that the higher-order root mean square (RMS) values seemed to be more strongly correlated with the decentration in the wavefront-modified aspheric IOL, but this may be due to just one IOL that was decentered by more than 1 mm. Most of the IOLs were decentered by less than 0.5 mm.
"Therefore, the effect of decentration on higher-order RMS values, which should mainly be attributed to coma, may be stronger in wavefront-modified IOLs than in spheric IOLs if a significant decentration is present. Clinically, however, this had no effect on the visual outcome," Dr. Baumeister reported.
He cautioned that a larger study is needed to support this conclusion.