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Journal of Sensors and Sensor Systems An open-access peer-reviewed journal
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Volume 7, issue 1
J. Sens. Sens. Syst., 7, 123-130, 2018
https://doi.org/10.5194/jsss-7-123-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
J. Sens. Sens. Syst., 7, 123-130, 2018
https://doi.org/10.5194/jsss-7-123-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular research article 05 Mar 2018

Regular research article | 05 Mar 2018

The influence of intraocular pressure on the damping of a coupled speaker–air–eye system

Jan Osmers1, Ágnes Patzkó2, Oskar Hoppe1, Michael Sorg1, Axel von Freyberg1, and Andreas Fischer1 Jan Osmers et al.
  • 1Bremer Institut für Messtechnik, Automatisierung und Qualitätswissenschaft (BIMAQ), Linzer Str. 13, 28359 Bremen, Germany
  • 2Augenklinik und Poliklinik, Universitätsklinikum Würzburg, Josef Schneider Str. 11, 97080 Würzburg, Germany

Abstract. Although glaucoma is currently the world's most common cause of irreversible blindness, there is no curative therapy available to date. The major risk factor that can be influenced in order to stop disease progression is the eye pressure (IOP). Therefore early diagnosis of an altered IOP is essential for the goal of preserving vision. A novel IOP measurement principle for a handheld noncontact self-tonometer shall be validated.

The measurement principle uses a pressure pulse generated by a loudspeaker to cause vibrations of the eye. In order to reach the required sound pressure, a closed pressure chamber is placed on the human orbit. With a microphone and a displacement sensor the dynamic behavior of the entire system is detected. In this article the abovementioned principle is being analyzed on porcine eyes under laboratory conditions.

The combination of the loudspeaker, the pressure chamber, and the eye to be measured can be described as a coupled spring–mass–damper system. It is demonstrated for enucleated porcine eyes that a defined IOP variation leads to a change in the system's damping ratio. Considering only stochastic deviations, the derived standard uncertainty for the determination of the IOP amounts to  <  1mmHg in the physiological range.

The in vitro measurements on porcine eyes help the understanding of the underlying physics and demand for further research on the influence of biometric parameters on eye vibrations. However, the laboratory results provide the basis for a gentle noncontact tonometry method with great applicational prospects. Data is currently being collected on human subjects in a clinical trial, to corroborate the measurement principle in vivo.

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Short summary
Glaucoma is the leading cause of irreversible blindness worldwide. The laboratory results of a novel measurement approach for the internal eye pressure are presented, with an uncertainty of less than 1 mmHg. A physical model explaining the relation between eye pressure and the damping ratio of a coupled mechanical system is defined. This provides design parameters for a handheld self-tonometer for Glaucoma diagnosis and therapeutic follow-up, with high application potential in ophthalmology.
Glaucoma is the leading cause of irreversible blindness worldwide. The laboratory results of a...
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