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Theoretic scientific rationale of double XEN 45 Gel Stent implant in severe glaucomatous ocular hypertension

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Abstract

Purpose

To investigate the theoretical hydrodynamic effects of a single or a double XEN 45 Gel Stent (XEN45) implant in glaucomatous eyes.

Methods

A prospective non-randomized clinical study on 63 glaucomatous eyes of 63 patients. The preoperative intraocular pressure (IOP) values after 14 days of medical therapy washout was correlated to the postoperative IOP values 7 and 45 days after the implant of a XEN45.

A mathematical model based on the Hagen-Poiseuille law was designed to assess the residual aqueous humor outflow (AHO) facility in glaucomatous eyes in function of the postoperative IOP reduction. Using XEN45 as unit of measurement, we transformed through equations the residual preoperative AHO in XEN45 equivalent in order to establish theoretical number of stents needed to reach the target IOP.

Results

The mean preoperative washout IOP was 28.9 ± 5.4 mmHg, after 7 and 45 days the mean postoperative IOP was 12.6 ± 4.3 and 15.3 ± 4.4 mmHg, respectively (p < 0.001). A significant positive correlation was found between preoperative and postoperative IOP values. We obtained a mathematical relationship to estimate the theoretical number of XEN45 stents needed to reach the target IOP.

Conclusion

The basal IOP (after medical therapy washout) is a predictive factor for the surgical success after a XEN45 implant. Establishing the residual preoperative AHO it is possible to predict the theoretical number of stents to implant.

A double XEN45 implant could be considered a possible further tool to reach the target IOP in patients with severe AHO deficiency.

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Acknowledgements

Special thanks to Eng. Marcello Montali for the scientific support with the mathematical analysis.

Funding

The authors declare that no funds, grants or other support were received during the preparation of this manuscript.

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Author notes

  1. Alessandra De Gregorio and Margherita Montali have contributed equally to this work.

Authors and Affiliations

  1. Ophthalmic Unit, San Bassiano Hospital, Bassano del Grappa, Italy

    Alessandra De Gregorio, Margherita Montali, Giulia Stevan & Simonetta Morselli

  2. Eye Clinic, Department of Neuroscience, Biomedicine and Mouvement, University of Verona, Verona, Italy

    Emilio Pedrotti

Authors
  1. Alessandra De Gregorio
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  2. Margherita Montali
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  3. Giulia Stevan
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  4. Emilio Pedrotti
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  5. Simonetta Morselli
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Contributions

All authors contributed to the study conception and design. Material preparation, data collections and analyses were performed by ADG, MM and GS. The first draft of the manuscript was written by ADG and MM. EP and SM: revised and approved the final version to be published.

Corresponding author

Correspondence to Alessandra De Gregorio.

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Conflict of interest

The authors have no relevant financial or non-financial interests to disclose.

Consent to participate

Informed consent was obtained from all individual participants included in the study.

Consent to publish

The authors affirm that human research participants provided informed consent for publication of the images in Fig. 4.

Ethics approval

This study was performed in line with the principles of the Declaration of Helsinki and did not require ethical approval since all patients were treated and followed as routine clinical practice.

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De Gregorio, A., Montali, M., Stevan, G. et al. Theoretic scientific rationale of double XEN 45 Gel Stent implant in severe glaucomatous ocular hypertension. Int Ophthalmol 43, 1629–1638 (2023). https://doi.org/10.1007/s10792-022-02561-6

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  • DOI: https://doi.org/10.1007/s10792-022-02561-6

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