April 2009
Volume 50, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2009
Clinical Application of a Digital Head Posture Measuring System for Pediatric Patients
Author Affiliations & Notes
  • E. S. Hald
    Ophthalmology/Bioengineering,
    University of Pittsburgh, Pittsburgh, Pennsylvania
  • R. W. Hertle
    Ophthalmology,
    University of Pittsburgh, Pittsburgh, Pennsylvania
  • D. Yang
    Ophthalmology,
    University of Pittsburgh, Pittsburgh, Pennsylvania
  • Footnotes
    Commercial Relationships  E.S. Hald, None; R.W. Hertle, None; D. Yang, None.
  • Footnotes
    Support  Fight For Sight Summer Studentship
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 1979. doi:
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      E. S. Hald, R. W. Hertle, D. Yang; Clinical Application of a Digital Head Posture Measuring System for Pediatric Patients. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1979.

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

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Abstract

Purpose: : We have developed a digital head posture measuring system (DHP) and previously reported its validity tested with an artificial head and normal subjects in 3D positions (Yang, et. al 2007, Hald, et. al 2008). Now, we report its repeatability and accuracy of measurements performed in pediatric patients.

Methods: : All testing was performed with IRB approval. The DHP consists of a head-mounted electronic compass, a standard PC, and customized software to sample and display 3D head posture in real time. It is mounted on a wire frame, similar to eyeglass frames. For repeatability tests (10 subjects), patient was instructed to view an image at a distance of 170 mm. The device was calibrated to zero when the patient reached their anomalous head posture. The patient’s head was then manually moved to the true zero position in 3D space by the investigator, and values for simultaneous yaw, pitch, and roll were sampled. Accuracy tests (5 subjects) involved the same basic procedure as repeatability tests but included the addition of a manual head posture measuring device (MHP) to calculate actual angle of measurement for statistical comparison (Yang, et. al 2007, Hald, et. al 2008). Repeatability values were found for repeatability tests and accuracy data were analyzed using a matched paired t-test to determine if differences between MHP and DHP angles are significant.

Results: : The DHP showed consistent outcomes compared with the MHP. Four subjects displayed pitch head postures, five displayed yaw head postures, and one displayed roll head postures. Match pairs t-tests for the difference between MHP and DHP head posture angles showed no significant difference between MHP and DHP angles for pitch, yaw and roll head postures (p > 0.05 for all three). Seven of the repeatability test subjects displayed noticeable yaw head postures, two displayed pitch head postures and three displayed roll head postures. After removing high and low angles from each subject’s data set, pitch subjects yielded 95% repeatability values ranging from 6-14 degrees. Yaw and roll subjects yielded repeatability values ranging from 3-23 degrees and 4-17 degrees, respectively.

Keywords: eye movements • clinical (human) or epidemiologic studies: systems/equipment/techniques • nystagmus 
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