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Effect of IOL misalignment on the optical performance of customised IOL designs for normal cataractous eyes and eyes with keratoconus

Poster Details

First Author: S.Schröder GERMANY

Co Author(s):    W. Liu   J. Schrecker   T. Eppig   A. Langenbucher           

Abstract Details


To evaluate the effect of misalignment of customized Intraocular lens (IOL) designs on the optical performance for normal eyes and eyes with keratoconus, and to compare the results with the performance of a standard aberration-neutral IOL design using individualized simulation model-eyes.


Saarland University, Institute of Experimental Ophthalmology, Homburg/Saar (Germany) Rudolf-Virchow-Klinikum Glauchau, Department of Ophthalmology, Glauchau (Germany) Department of Ophthalmology, Saarland University Medical Center, Homburg/Saar (Germany)


Three types of IOLs were compared based on their weighted root-mean-square spot size on the retina (wRMS): (#1) an aberration-neutral IOL, (#2) an aberration-correcting freeform-IOL customized for each eye, and (#3) an IOL based on 22 Zernike-polynomial terms designed to be less affected by IOL-misalignment compared to model #2. The comparison uses Monte-Carlo analysis for a simulated clinical study with 12 eyes per group and 500 virtual IOL-implantations per eye. Upon each virtual implantation, IOL-misalignment (lateral and axial displacement, tilt, and rotation) and iris-position were varied randomly according to variation-ranges that had been observed in clinical studies.


In normal and keratoconic eyes, IOL-model #2 performed better than model #1 in >87% while IOL-design #3 outperformed model #1 in >91% of the 6,000 virtual implantations per group. The average wRMS was 16.4µm ± 4.2µm, 9.5µm ± 5.8µm, 9.9µm ± 4.9µm in normal eyes and 92.7µm ± 34.4µm, 23.4µm ± 17.6µm, 24.7µm ± 16.4µm in keratoconic eyes with IOL-Model #1, #2, and #3, respectively (mean ± standard-deviation). Correlation analysis showed that the wRMS was most affected by IOL-tilt and pupil decentration for model #1 and by lateral IOL-diplacement for the custom IOL-models (#2,#3).


Custom IOLs (#2, #3) resulted in improved average wRMS compared to model #1. However, the custom IOLs were more affected by lateral IOL displacement. The IOL-design #3 reduced the effect of IOL-misalignment compared to IOL-design #2. The custom IOLs for eyes with keratoconus could improve the wRMS to levels comparable with the wRMS achieved with model #1 in normal eyes. Custom, freeform IOL-optics-designs may become an option for the correction keratoconic or highly aberrated eyes with stable corneal tomography in cataract surgery or refractive lens exchange even if a moderate IOL-misalignment (<0.8mm) occurs.

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