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Development of a program for toric intraocular lens calculation considering posterior corneal astigmatism, incision-induced posterior corneal astigmatism, and effective lens position

Abstract

Background

To evaluate the toric intraocular lens (IOL) calculation considering posterior corneal astigmatism, incision-induced posterior corneal astigmatism, and effective lens position (ELP).

Methods

Two thousand samples of corneal parameters with keratometric astigmatism ≥ 1.0 D were obtained using bootstrap methods. The probability distributions for incision-induced keratometric and posterior corneal astigmatisms, as well as ELP were estimated from the literature review. The predicted residual astigmatism error using method D with an IOL add power calculator (IAPC) was compared with those derived using methods A, B, and C through Monte-Carlo simulation. Method A considered the keratometric astigmatism and incision-induced keratometric astigmatism, method B considered posterior corneal astigmatism in addition to the A method, method C considered incision-induced posterior corneal astigmatism in addition to the B method, and method D considered ELP in addition to the C method. To verify the IAPC used in this study, the predicted toric IOL cylinder power and its axis using the IAPC were compared with ray-tracing simulation results.

Results

The median magnitude of the predicted residual astigmatism error using method D (0.25 diopters [D]) was smaller than that derived using methods A (0.42 D), B (0.38 D), and C (0.28 D) respectively. Linear regression analysis indicated that the predicted toric IOL cylinder power and its axis had excellent goodness-of-fit between the IAPC and ray-tracing simulation.

Conclusions

The IAPC is a simple but accurate method for predicting the toric IOL cylinder power and its axis considering posterior corneal astigmatism, incision-induced posterior corneal astigmatism, and ELP.

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Authors and Affiliations

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Correspondence to Hyo Myung Kim.

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Funding

This study was supported in part by the SRC program (2010-0027910) of the Center for Galaxy Evolution Research (CGER), by the Korea Astronomy and Space Science Institute under the R&D program (Project No. 2014-9-710-03) supervised by the Ministry of Science, ICT and Future Planning, South Korea, and by the Busan Sungmo Eye Hospital Sodam Scholarship Committee, Busan, South Korea. The sponsor had no role in the design or conduct of this research.

Conflict of interest

All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements) or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required.

Financial disclosure

None.

Additional information

This work was presented in part at XXXIII Congress of the European Society of Cataract & Refractive Surgeons (ESCRS), Barcelona, Spain, 2015.

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Eom, Y., Ryu, D., Kim, D.W. et al. Development of a program for toric intraocular lens calculation considering posterior corneal astigmatism, incision-induced posterior corneal astigmatism, and effective lens position. Graefes Arch Clin Exp Ophthalmol 254, 1977–1986 (2016). https://doi.org/10.1007/s00417-016-3446-3

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  • DOI: https://doi.org/10.1007/s00417-016-3446-3

Keywords

  • Toric intraocular lens
  • Posterior corneal astigmatism, Incision-induced astigmatism
  • Effective lens position