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Comparing refractive outcomes of a standard industry toric IOL calculator using anterior corneal astigmatism and total corneal refractive power

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Abstract

Purpose

To evaluate refractive outcomes for a standard industry calculator using anterior corneal astigmatism or total corneal refractive power.

Methods

This prospective interventional study evaluated the refractive outcomes of 56 eyes using a standard industry calculator (Zeiss ZCalc) and a digital IOL alignment software. After A-constant optimisation the ZCalc was recalculated with two different keratometry values using appropriate refractive indices: anterior corneal astigmatism (ACA) by IOLMaster 700 and total corneal refractive power (TCRP) by Pentacam. The Barrett toric calculator was used as a reference.

Results

Undercorrection of 0.04 ± 0.42 D after 1 week and 0.13 ± 0.48 D after 3 months was achieved for the spherical equivalent by using a standard industry calculator. IOL misalignment was 2.8° ± 3.4° using a digital alignment system. For the ZCalc, the mean absolute error could be reduced from 0.19 ± 0.40 D using ACA to 0.04 ± 0.48 D when considering total corneal refractive power (p = 0.06). The Barrett calculator delivered better refractive outcomes than using a standard industry calculator with ACA measurements only (− 0.06 ± 0.43 D; p < 0.01).

Conclusion

Reliable and accurate refractive outcomes in toric IOL calculation were achieved by using the ZCalc calculator. The prediction error for a widely used standard industry toric IOL calculator could be reduced by using measured total corneal refractive power.

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Funding

Christoph Kern received a research grant from Bayer AG. Linda El Kaissi has nothing to declare. Karsten Kortuem received a research grant from Bayer AG and speaker fees from Carl Zeiss Meditech. Mehdi Shajari is a consultant for Oculus. Efstathios Vounotripidis has nothing to declare. Achim Langenbucher has nothing to declare. Siegfried Priglinger received speaker fees from Alcon, Polytech/Domilens, Örtli, Novartis and Carl Zeiss Meditech. Wolfgang Mayer received financial support by Alcon, Carl Zeiss Meditech, Ziemer, Allergan, Oculentis, Novartis, Bausch&Lomb, Heidelberg Engineering, Örtli and Staar Surgical.

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Authors and Affiliations

  1. Department of Ophthalmology, University Hospital, LMU Munich, Mathildenstraße 8, 80336, Munich, Germany

    C. Kern, L. El Kaissi, K. Kortuem, M. Shajari, E. Vounotrypidis, S. Priglinger & W. J. Mayer

  2. Institute of Experimental Ophthalmology, Saarland University, Saarbrücken, Germany

    A. Langenbucher

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  1. C. Kern
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  2. L. El Kaissi
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  7. S. Priglinger
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Correspondence to C. Kern.

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All procedures performed in studies involving human participants were in accordance with the ethical standards of the University Hospital Munich, LMU, Germany, and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Ethical approval was obtained by the university’s ethics committee under the approval number 17-875. Informed consent was obtained from all individual participants included in the study.

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Kern, C., El Kaissi, L., Kortuem, K. et al. Comparing refractive outcomes of a standard industry toric IOL calculator using anterior corneal astigmatism and total corneal refractive power. Graefes Arch Clin Exp Ophthalmol 258, 345–350 (2020). https://doi.org/10.1007/s00417-019-04570-1

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  • DOI: https://doi.org/10.1007/s00417-019-04570-1

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