Waveform type evaluation in congenital nystagmus

Giulio Pasquariello, Mario Cesarelli*, Maria Romano, Antonio la Gatta, Paolo Bifulco, Antonio Fratini

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Congenital nystagmus is an ocular-motor disorder characterised by involuntary, conjugated and bilateral to and fro ocular oscillations. In this study a method to recognise automatically jerk waveform inside a congenital nystagmus recording and to compute foveation time and foveation position variability is presented. The recordings were performed with subjects looking at visual targets, presented in nine eye gaze positions; data were segmented into blocks corresponding to each gaze position. The nystagmus cycles were identified searching for local minima and maxima (SpEp sequence) in intervals centred on each slope change of the eye position signal (position criterion). The SpEp sequence was then refined using an adaptive threshold applied to the eye velocity signal; the outcome is a robust detection of each slow phase start point, fundamental to accurately compute some nystagmus parameters. A total of 1206 slow phases was used to compute the specificity in waveform recognition applying only the position criterion or adding the adaptive threshold; results showed an increase in negative predictive value of 25.1% using both features. The duration of each foveation window was measured on raw data or using an interpolating function of the congenital nystagmus slow phases; foveation time estimation less sensitive to noise was obtained in the second case.

Original languageEnglish
Pages (from-to)49-58
Number of pages10
JournalComputer Methods and Programs in Biomedicine
Volume100
Issue number1
Early online date31 Mar 2010
DOIs
Publication statusPublished - Oct 2010

Keywords

  • congenital nystagmus
  • foveation window
  • interpolation
  • waveform recognition

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