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Topography-based intraocular lens power selection.

Paul-Rolf Preussner·Jochen Wahl·Daniela Weitzel
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Abstract

PURPOSE: To provide mathematical tools for selecting intraocular lens (IOL) power for normal eyes and for "odd" eyes, particularly after corneal refractive surgery. SETTING: Universitats-Augenklinik, Mainz, Germany. METHODS: First, IOL power is selected based on the radii and numerical eccentricity of the cornea, extracted from corneal topography in a consistent numerical model of the cornea. To fine-tune the result, the visual impression is simulated by blurred Landolt rings superimposed on the retinal receptor grid. The calculation uses numerical ray tracing of the whole pseudophakic eye comprising all monochromatic errors. The error contributions of the influencing parameters, such as anterior and posterior corneal shape and corneal thickness, are quantified in detail. The method is verified in IOL power selection for normal eyes and for eyes after corneal refractive surgery. RESULTS: The main difference between normal corneas and corneas after refractive surgery results from different asphericities. Normal corneas are prolate, with typical numerical eccentricities of 0.5, whereas corneas after laser surgery for myopia are oblate. This causes the main difference (hyperopic shift up to 2.0 diopters) in IOL power selection. Shifts in the posterior corneal radius and corneal thickness are of minor importance. CONCLUSION: Intraocular power selection after corneal refractive surgery should be based on all the information corneal topography provides.

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Cataract ExtractionCorneaCorneal TopographyHumansLenses, IntraocularMathematicsModels, TheoreticalOptics and PhotonicsRefractive Surgical ProceduresJournal Article

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Paul-Rolf Preussner, Jochen Wahl, Daniela Weitzel. 2005. Topography-based intraocular lens power selection.. https://doi.org/10.1016/j.jcrs.2004.09.016

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