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Simulated and measured intensities and losses of trifocal IOLs at different wavelengths

Poster Details

First Author: W.Brezna AUSTRIA

Co Author(s):    N. Plank   K. Lux   N. Dragostinoff   G. Garhofer           

Abstract Details


The purpose of this work was to investigate the possibility to simulate especially the losses (LOSS) of diffractive trifocal intraocular lenses (IOLs), besides the intensity distribution at the distant (DIST), intermediate (INTER) and near (NEAR) foci. This would make it possible to optimize respectively minimize the light losses in trifocal IOLs. Therefore, simulated and measured intensity distributions and losses of a prototype lens (LP) were compared for three wavelengths. Furthermore, the intensity distributions and loss values of a commercial trifocal lens (LC) were measured at three wavelengths ranging from blue to red color.


An optical bench setup (Trioptics Optispheric IOL) was used to perform the measurements. A field tracing software (VirtualLab Fusion from Lighttrans GmbH) was used for the simulation work. Segmentation of the measurement data into desired signal and losses was done via custom developed Matlab code.


The investigated IOLs (LP and LC) were measured inside the ISO 11979 conform model eye of the optical bench setup. At the three main foci, high dynamic range images of the point spread function were recorded. A Matlab algorithm was applied to split the image data into a useful share (forming the different foci) and a non-useful share (forming the losses). Field tracing via VirtualLab was applied for the simulation. For validation purposes, the simulated results were compared to measurements of a prototype trifocal IOL LP of known design at three wavelengths 488nm (blue), 546nm (green) and 650nm (red).


Measured intensity distributions of the prototype lens LP for DIST – INTER – NEAR – LOSS were 42.1% - 13.9% - 28.5% - 15.5% (green), 44.7% - 3.6% - 39.7% - 12.0% (blue), and 22.4% - 47.5% - 10.0% - 20.1% (red). The simulated distribution for the LP was 38.0% - 13.2% - 22.4% - 26.3% (green), and 39.3% - 3.0% - 30.7% - 27.0% (blue). The measured distribution for the commercial lens LC was 44.1% - 16.5% - 24.8% - 14.6% (green), 33.1% - 19.1% - 31.0% - 16.8% (blue), and 53.2% - 11.1% - 17.4% - 18.3% (red).


For the prototype lens LP, the simulated and measured intensity distribution values agreed very well, if only the relative distribution of DIST, INTER and NEAR are considered alone. For the LOSS value, simulation and measurement did not agree. From an analysis of the simulated images the authors conclude that it is very likely that there are some parasitic effects within the simulations, which distribute or scatter the simulated intensities stronger than observed in reality, and lead to the observed deviation in the LOSS values.

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