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Do aberration neutral intraocular lens designs effectively induce no spherical aberration?

Poster Details

First Author: T.Eppig GERMANY

Co Author(s):    S. Schroeder   J. Schrecker   A. Langenbucher              

Abstract Details


Currently, there are two different concepts of �â�€�œaberration neutral�â�€� intraocular lens (IOL) designs available on the market. One adds no spherical aberration (SA) when tested with a parallel beam, the second adds no SA in a converging beam similar to the situation in the eye. The purpose of this study was to evaluate the difference between these two different concepts of aberration neutral IOL designs.


Institute of Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany


We implemented two scenarios in an optical design software. First, we placed an IOL model in a parallel beam and optimized the anterior surface to eliminate SA (parIOL). Second, we used a converging beam (43 D) in front of the IOL model and optimized the IOL surface accordingly (conIOL). Both IOL models were designed with the same back surface. Subsequently, the IOL models were tested in the opposite environment (i.e.g. conIOL in parallel beam and parIOL with converging beam). The resulting SA and the Strehl ratio (SR) were calculated and compared to a spherical and to an aberration correcting IOL.


Both aspheric IOL models induced no SA in the setting they were designed for. When tested in the opposite setting, the concepts behaved differently. The parIOL induced �.23 �Â�µm SA, which was less than that of a spherical IOL (�.36 �Â�µm) in this setting. The conIOL showed -0.21 �Â�µm SA when tested in the parallel beam, which was less than with an aberration correcting IOL (-0.38 �Â�µm) but more than with a spherical IOL (�.12 �Â�µm). The conIOL showed 0.95/0.28 SR in the converging/parallel beam. The parIOL showed 0.23/0.99 SR and the spherical IOL 0.14/0.35 SR, respectively.


�â�€�œAberration neutral�â�€� IOL may reveal unexpected results when tested on an optical bench. Lens designs may appear as non-neutral (i.e.g. either inducing positive or negative spherical aberration) depending on the test environment. Especially designs optimized in junction with a model cornea (converging beam) may be mistaken as aberration correction lenses when tested in parallel beams according to ISO 11979-2, which is the case in many IOL testing devices.

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