May 2006
Volume 47, Issue 13
ARVO Annual Meeting Abstract  |   May 2006
Testing of a Personal Tonometer Prototype for Measuring IOP
Author Affiliations & Notes
  • I. Nwosuh
    NJIT, Newark, NJ
  • T. Alvarez
    NJIT, Newark, NJ
    Biomedical Engineering,
  • A.S. Khouri
    Ophthalmology, UMDNJ, Newark, NJ
  • R.D. Fechtner
    Ophthalmology, UMDNJ, Newark, NJ
  • G.A. Thomas
    NJIT, Newark, NJ
  • Footnotes
    Commercial Relationships  I. Nwosuh, None; T. Alvarez, None; A.S. Khouri, None; R.D. Fechtner, None; G.A. Thomas, None.
  • Footnotes
    Support  NJ Commission on Science and Technology; National Medical Technology Testbed; Research to Prevent Blindness
Investigative Ophthalmology & Visual Science May 2006, Vol.47, 4434. doi:
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      I. Nwosuh, T. Alvarez, A.S. Khouri, R.D. Fechtner, G.A. Thomas; Testing of a Personal Tonometer Prototype for Measuring IOP . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4434.

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

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Purpose: : A personal tonometer for intra–ocular pressure (IOP) (analogous to a personal glucometer) is believed to be a useful tool that would aid in the diagnosis and monitoring of glaucoma. We have constructed a tonometer designed for trans–palpebral use and tested it on an artificial eye with variable pressure.

Methods: : Electronic signals from the tonometer’s force and position sensors were passed through a Kiethley amplifier to a National Instruments Analog to Digital converter, then to a portable computer for analysis. The measurement curves were made three times for each pressure in the artificial eye, and the pressure was read with a water manometer. In the tests with the artificial eye, the range of forces from 0 to 3 grams was explored with an application area produced by a 3mm diameter cylinder. The displacement distances for the artificial cornea were 0 to 1mm.

Results: : The force curves as a function of displacement all showed curvature for displacements in the range of 0 to 0.2mm, with linear behavior at higher displacement with correlations of 0.98. The slopes were reproducible using the artificial eye with a mean difference of 0.01 to 0.03 within any given set of 3 measurements for 30 sets of measurements. The slopes scale with the manometer pressure according to a linear relationship with a correlation factor of 0.97 and p=0.0065.

Conclusions: : The tonometer output shows a satisfactory correlation with pressure in lab trials, and indicates that measurements on human subjects are appropriate and may provide a practical approach for personal tonometry.

Keywords: intraocular pressure • clinical laboratory testing 

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