Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Aug;39(12):2423-2428.
doi: 10.1038/s41433-025-03870-7. Epub 2025 Jun 11.

In vitro flow properties of Preserflo Michroshunt with an intraluminal stent

Enrico Lupardi  1   2   3 , Antonio Cassiano  4 , Antonio Moramarco  4   5 , Luigi Fontana  4   5 , Ivan Corazza #  6 , Keith Barton #  7
Affiliations

In vitro flow properties of Preserflo Michroshunt with an intraluminal stent

Enrico Lupardi et al. Eye (Lond). 2025 Aug.

Abstract

Objectives: This study aimed to evaluate the impact of varying stent sizes and materials on the outflow of the Preserflo Microshunt (PMS).

Methods: In vitro experiments were conducted using five new PMS samples. Intraluminal stents of two materials (nylon and polypropylene) and two sizes (9-0 and 10-0) were tested. Flow was measured using a balanced saline solution (BSS) under a constant hydrostatic pressure, and the resistance was calculated. Theoretical calculations based on the Hagen-Poiseuille law were compared with in vitro results, and the results were corrected to calculate resistance to flow using aqueous humour properties. Five measurements were obtained for each material and size.

Results: Without any stent, the median resistance internal to PMS corrected for aqueous humour viscosity was 1.59 mmHg/µL/min. Median resistances were 6.35 mmHg/µL/min (range: 3.88-7.42) for the 10-0 nylon and, 11.79 mmHg/µL/min (range: 7.08-13.71) for the 10-0 polypropylene. The 9-0 stents showed higher resistance: 10.99 mmHg/µL/min (range: 7.34-22.75) for 9-0 nylon, finally, the 9-0 polypropylene resulted in a resistance of 37.55 mmHg/µL/min (range: 36.52-38.41).

Conclusions: This study indicates that the tested suture materials and sizes have a significant impact on the outflow resistance of the PMS device. Larger sutures and/or polypropylene materials seem to offer more resistance to aqueous outflow.

PubMed Disclaimer

Conflict of interest statement

Competing interests: The authors declare no competing interests.

References

    1. Pinchuk L, Riss I, Batlle JF, Kato YP, Martin JB, Arrieta E, et al. The development of a micro-shunt made from poly(styrene-block-isobutylene-block-styrene) to treat glaucoma. J Biomed Mater Res B Appl Biomater. 2017;105:211–21. - PMC - PubMed
    1. Pinchuk L, Riss I, Batlle JF, Kato YP, Martin JB, Arrieta E, et al. The use of poly(styrene- block -isobutylene- block -styrene) as a microshunt to treat glaucoma. Regen Biomater. 2016;3:137–42. - PMC - PubMed
    1. Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC. Surgical complications in the tube versus trabeculectomy study during the first year of follow-up. Am J Ophthalmol. 2007;143:23–31.e2. - PubMed
    1. Thomas M, Vajaranant TS, Aref AA. Hypotony maculopathy: clinical presentation and therapeutic methods. Ophthalmol Ther. 2015;4:79–88. - PMC - PubMed
    1. Molteno ACB, Fucik M, Dempster AG, Bevin TH. Otago Glaucoma Surgery Outcome Study: factors controlling capsule fibrosis around Molteno implants with histopathological correlation. Ophthalmology. 2003;110:2198–206. - PubMed

LinkOut - more resources