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Prediction of spectacle refraction uncertainties with discrete IOL power steps and manufacturing tolerances according to ISO using a Monte Carlo model
  1. Achim Langenbucher1,
  2. Nóra Szentmáry2,3,
  3. Alan Cayless4,
  4. Matthias Bolz5,
  5. Peter Hoffmann6,
  6. Jascha Wendelstein1,7
  1. 1Department of Experimental Ophthalmology, Saarland University, Homburg, Germany
  2. 2Dr. Rolf M. Schwiete Center for Limbal Stem Cell and Aniridia Research, Saarland University Hospital and Faculty of Medicine, Homburg, Germany
  3. 3Department of Ophthalmology, Semmelweis University of Medicine, Budapest, Hungary
  4. 4School of Physical Sciences, The Open University, Milton Keynes, UK
  5. 5Department of Ophthalmology, Kepler University Hospital, Linz, Austria
  6. 6Augen-und Laserklinik Castrop-Rauxel, Castrop-Rauxel, Germany
  7. 7Department of Ophthalmology, Johannes Kepler University, Linz, Austria
  1. Correspondence to Dr Achim Langenbucher, Department of Experimental Ophthalmology, Saarland University, Homburg, 66421, Germany; achim.langenbucher{at}


Purpose The purpose of this study was to develop a concept for predicting the effects of both discrete intraocular lens (IOL) power steps (PS) and power labelling tolerances (LT) on the uncertainty of the refractive outcome (REFU).

Design Retrospective non-randomised cross-sectional Monte Carlo simulation study.

Methods We evaluated a dataset containing 16 669 IOLMaster 700 preoperative biometric measurements. The PS and the delivery range of two modern IOLs (Bausch and Lomb enVista and Alcon SA60AT) were considered for this Monte Carlo simulation. The uncertainties from PS or LT were assumed to be normally distributed according to ±½ the IOL PS or the ISO 11979 LT. REFU was recorded and analysed for all simulations.

Results With both lenses the REFU from discrete PS ranged from 0.11 to 0.12 dpt. Due to the larger PS for low/high power lenses with the enVista/SA60AT, REFU is more dominant in initially myopic/hyperopic eyes. REFU from LT ranged from 0.18 to 0.19 dpt for both lenses. Since LT increases stepwise with IOL power, REFU is more prevalent in initially hyperopic eyes requiring high IOL power values, and for lenses with a wide delivery range towards higher powers.

Conclusions Since surgeons and patients are typically aware of the effect of discrete PS on REFU, these might be tolerated in cataract surgery. However, REFU resulting from LT is inevitable while the true measured IOL power is not reported on the package, leading to background noise in postoperative achieved refraction.

  • Optics and Refraction
  • Lens and zonules

Data availability statement

Data are available upon request.

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Data availability statement

Data are available upon request.

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  • Contributors Concept and design of the study: AL, NS, AC, MB, PH, and JW; Data acquisition: PH; Data analysis/interpretation: AL, NS, MB, PH, and JW; Drafting of the manuscript: AL, NS, AC, MB, PH, and JW; Critical revision of the manuscript: AL, NS, AC, MB, PH, and JW; Administrative, technial or material support: NS, MB, and JW; Supervision: AL, AC, NS, JW. AL is guarantor.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests AL reports speaker fees from PH Surgical and J&J Vision outside the submitted work. NS and AC do not report any financial interests. MB reports speaker fees from CZM, AG outside the submitted work. PH reports speaker fees from Heidelberg engineering, PH Surgical and J&J outside the submitted work. JW reports speaker fees from CZ Meditec AG, Alcon and J&J Vision outside of the submitted work.

  • Provenance and peer review Not commissioned; externally peer reviewed.