June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Application of a novel pneumatic intraocular pressure modulator: technical confounding of the tonographic effect
Author Affiliations & Notes
  • Dietmar Link
    Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, Germany
  • Benedikt Krauss
    Imedos Systems GmbH, Jena, Germany
  • Richard Stodtmeister
    Department of Ophthalmology, University Hospital Carl Gustav Carus, Technische Universitat Dresden, Dresden, Sachsen, Germany
    Augenarzt, Augenspezialisten Saar, Völklingen, Germany
  • Edgar Nagel
    Ophthalmic Private Practice, Rudolstadt, Germany
  • Walthard Vilser
    Imedos Systems GmbH, Jena, Germany
  • Sascha Klee
    Department of General Health Studies, Division Biostatistics and Data Science, Karl Landsteiner University of Health Science, Krems, Austria
    Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, Germany
  • Footnotes
    Commercial Relationships   Dietmar Link None; Benedikt Krauss None; Richard Stodtmeister None; Edgar Nagel None; Walthard Vilser None; Sascha Klee None
  • Footnotes
    Support  Supported by the German Federal Ministry of Economic Affairs and Energy (BMWi) as part of a ZIM project (Grant ZF 4112006AW9) and the Carl Zeiss Stiftung.
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 161 – A0354. doi:
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      Dietmar Link, Benedikt Krauss, Richard Stodtmeister, Edgar Nagel, Walthard Vilser, Sascha Klee; Application of a novel pneumatic intraocular pressure modulator: technical confounding of the tonographic effect. Invest. Ophthalmol. Vis. Sci. 2022;63(7):161 – A0354.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : From several studies in occulopression, repeated tonometry or ophthalmodynamometry we have knowledge that the intraocular pressure (IOP) decreases during an artificial IOP increase. This phenomenon is known as the tonographic effect. In healthy eyes an IOP drop of 2–3 mmHg/min was reported. However, there are studies that show a reduced decrease of the IOP drop for instance in glaucoma patients. In this work we determine the tonographic effect in healthy eyes by utilizing a novel pneumatic pressure modulator and validate the modulator technically in order to determine the technical confounding of the tonographic effect.

Methods : For technical validation and in vivo application, a pneumatic intraocular modulator (IOPstim, Imedos Systems GmbH, Jena, Germany) was used. A force sensor (KD34s, ME-Meßsysteme GmbH, Hennigsdorf, Germany) was placed in front of the balloon. Pressure stability was analyzed for 2 minutes. The force values were recorded for five different device target pressures from 50 mmHg to 250 mmHg in steps of 50 mmHg, and this sequence was repeated 10 times. A new balloon was used for each sequence. In the subject study, the IOP of 10 healthy subjects (6 male, 4 female, aged 28.8 ± 6.64 years) was modulated and increased linearly to at least 40 mmHg. At this point, the pressure inside the balloon was kept constant for 2 minutes, with IOP measurements taken every 40 seconds using a rebound tonometer (Icare PRO, Icare Finland Oy, Helsinki, Finland).

Results : The technical setup led to an IOP decrease of 0.7 mmHg within 2 minutes at an operating point of 40 mmHg IOP. In the subject study, the IOP could be increased up to 42.8 ± 3.6 mmHg for all subjects (n = 10), whereby a mean pressure decrease of 4.8 mmHg within 2 minutes was determined, which seems to be caused mainly by physiological processes.

Conclusions : With the new pneumatically based setup, a targeted modulation in terms of level and constancy of the IOP can be realized. Technical validation showed that the purely technical influence on the tonographic effect, i.e. the drop in IOP, carried 0.3 mmHg/min with a total effect of 2.4 mmHg/min. The technical confounding of the tonographic effect is clearly less than the physiological effect itself.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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