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Impact of lens density and lens thickness on cumulative dissipated energy in femtosecond laser–assisted cataract surgery

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Abstract

To evaluate the required cumulative dissipated energy (CDE) to fragment the crystalline lens in femtosecond laser–assisted cataract surgery (FLACS) in relation to lens density and lens thickness. Consecutive eyes that underwent FLACS between September 2014 and March 2017 by a single surgeon using in all cases the same femtosecond laser and phacoemulsification platform were included in our retrospective study. Prior to surgery, corrected distance visual acuity (CDVA), optical biometry corneal, and crystalline lens tomographies were performed to assess anterior chamber depth (ACD), axial length (AL), and crystalline lens parameters (i.e., lens density, thickness, and nucleus staging (NS)). After surgery, CDE was calculated and analyzed in relation to lens density (LD) and lens thickness (LT). Zero ultrasound expenditure cases were recorded and their occurrence analyzed. The chart review identified 236 eyes of 200 patients, 98 males and 102 females aged 65± 15 years which were included in the study. Mean LD was 11.26 ± 2.05 pixel intensity units (range 7.30–18.80), and the mean LT was 3417 ± 405.17 μm (range 2545–4701). LD and LT correlated moderately (r = 0.50, p < 0.001) and weakly (r = 0.23, p < 0.001), with post-laser CDE. Higher LD and LT were also associated with lower rates of zero phaco (eyes in which no phacoemulsification energy was necessary). Furthermore, NS (r = 0.528, p < 0.001) and CDVA (r = − 0.3524, p < 0.001) also correlated with CDE. Higher LD, LT, NS values, and low CDVA are associated with higher ultrasound expenditure (CDE—cumulative dissipated energy) and with lower rates of zero ultrasound expenditure during FLACS.

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Acknowledgements

Alison Rowan McEwan and Leon de’Lorenzo, Goethe University, Frankfurt, Germany, provided additional support in the proof reading and preparation of this manuscript.

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Authors and Affiliations

  1. Department of Ophthalmology, Goethe-University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany

    Mehdi Shajari, Vladimir Rusev, Kerstin Petermann & Thomas Kohnen

  2. Department of Ophthalmology, Ludwig Maximillian University, Munich, Germany

    Mehdi Shajari & Wolfgang Mayer

  3. Bascom Palmer Eye Institute, Miami, USA

    Vasilios Diakonis

Authors
  1. Mehdi Shajari
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  2. Vladimir Rusev
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  3. Wolfgang Mayer
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  4. Vasilios Diakonis
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  5. Kerstin Petermann
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  6. Thomas Kohnen
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Corresponding author

Correspondence to Thomas Kohnen.

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Ethical approval

The study was designed in compliance with the principles of the Declaration of Helsinki and approved by the local ethics committee. For this type of study, formal consent is not required.

Conflict of interest

Mehdi Shajari: Oculus, Zeiss, Staar, Santen, Oertli. Vladimir Rusev: none. Wolfgang Mayer: Consultant or Advisory Board—Alcon, Allergan, Polytech/Domilens, Zeiss Meditec, Ziemer. Vasilios Diakonis: none. Kerstin Petermann: none. Thomas Kohnen: Research Funding—Hoya, J&J Vision (Abbott), Novartis (Alcon), Oculentis, Oculus, Schwind, Zeiss. Consultant or Advisory Board—Geuder, J&J Vision (Abbott), Novartis (Alcon), Oculus, Santen, Schwind, STAAR, TearLab, Thea Pharma, Thieme Compliance, Ziemer, Zeiss. Consultant and Research for Abbott/J&J, Alcon/Novartis, Schwind, Zeiss. Consultant for Allergan, Bausch & Lomb, Dompe, Geuder, Med Update, Oculentis, Oculus, Rayner, Santen, Staar, Thea, Tear Lab, Thieme, Unimed Verlag, Ziemer. Research for Avedro, Hoya, Presbia.

The authors declare that they have no conflict of interest.

Additional information

Precis

Not just the central lens density but also the lens thickness has an impact on cumulative dissipated energy during femtosecond laser–assisted lens surgery.

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Shajari, M., Rusev, V., Mayer, W. et al. Impact of lens density and lens thickness on cumulative dissipated energy in femtosecond laser–assisted cataract surgery. Lasers Med Sci 34, 1229–1234 (2019). https://doi.org/10.1007/s10103-019-02715-6

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  • DOI: https://doi.org/10.1007/s10103-019-02715-6

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