An automated segmentation approach to calibrating infantile nystagmus waveforms

Dunn, Matthew; Harris, Christopher M.; Ennis, Fergal; Margrain, Thomas Hengist; Woodhouse, J. Margaret; McIlreavy, Lee; Erichsen, Jonathan Thor

doi:10.3758/s13428-018-1178-5

Cited by 13 publications

(9 citation statements)

References 24 publications

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“…In infantile nystagmus, drift and saccades alternate in a highly heterogeneous fashion and often vary extensively both within and between individuals. Recently, a calibration method has been suggested based on the automatic extraction of foveation periods according to relative velocity within the nystagmus slow phase periods, outlier correction, and waveform shape comparison (Dunn, Harris, Ennis, Margrain, Woodhouse, McIlreavy, & Erichsen, 2019;Rosengren, Nyström, Hammar, & Stridh, 2020). In the present study, we propose a different approach, one that defines the eye movements' start-and endpoints independent of the shape and uniformity of nystagmus waveforms.…”

Section: Discussionmentioning

confidence: 99%

Successful visually guided eye movements following sight restoration after congenital cataracts

et al. 2020

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Sensitive periods have previously been identified for several human visual system functions. Yet, it is unknown to what degree the development of visually guided oculomotor control depends on early visual experience-for example, whether and to what degree humans whose sight was restored after a transient period of congenital visual deprivation are able to conduct visually guided eye movements. In the present study, we developed new calibration and analysis techniques for eye tracking data contaminated with pervasive nystagmus, which is typical for this population. We investigated visually guided eye movements in sight recovery individuals with long periods of visual pattern deprivation (3-36 years) following birth due to congenital, dense, total, bilateral cataracts. As controls we assessed (1) individuals with nystagmus due to causes other than cataracts, (2) individuals with developmental cataracts after cataract removal, and (3) individuals with normal vision. Congenital cataract reversal individuals were able to perform visually guided gaze shifts, even when their blindness had lasted for decades. The typical extensive nystagmus of this group distorted eye movement trajectories, but measures of latency and accuracy were as expected from their prevailing nystagmus-that is, not worse than in the nystagmus control group. To the best of our knowledge, the present quantitative study is the first to investigate the characteristics of oculomotor control in congenital cataract reversal individuals, and it indicates a remarkable effectiveness of visually guided eye movements despite long-lasting periods of visual deprivation.

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Section: Discussionmentioning

confidence: 99%

Successful visually guided eye movements following sight restoration after congenital cataracts

et al. 2020

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“…Their high resolution, greater linearity, improved sampling rates and noise reduction properties are particularly important for examining nystagmus waveforms, which can vary from cycle to cycle. Advances in signal calibration of a moving eye 64 , 65 , together with new techniques for noise reduction of the data 66 , will no doubt assist in the analysis of a nystagmus time series. Moreover, targeted studies on nystagmus feature extraction 9 , 20 , 35 , 67 and modelling of nystagmus waveforms (see “ Mechanisms underlying the waveform complexity ” section) will improve our understanding of the mechanisms underpinning the oscillations.…”

Section: Discussionmentioning

confidence: 99%

Analysing nystagmus waveforms: a computational framework

Abadi

Akman

Arblaster

et al. 2021

Sci Rep

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We present a new computational approach to analyse nystagmus waveforms. Our framework is designed to fully characterise the state of the nystagmus, aid clinical diagnosis and to quantify the dynamical changes in the oscillations over time. Both linear and nonlinear analyses of time series were used to determine the regularity and complexity of a specific homogenous phenotype of nystagmus. Two-dimensional binocular eye movement recordings were carried out on 5 adult subjects who exhibited a unilateral, uniplanar, vertical nystagmus secondary to a monocular late-onset severe visual loss in the oscillating eye (the Heimann-Bielschowsky Phenomenon). The non-affected eye held a central gaze in both horizontal and vertical planes (± 10 min. of arc). All affected eyes exhibited vertical oscillations, with mean amplitudes and frequencies ranging from 2.0°–4.0° to 0.25–1.5 Hz, respectively. Unstable periodic orbit analysis revealed only 1 subject exhibited a periodic oscillation. The remaining subjects were found to display quasiperiodic (n = 1) and nonperiodic (n = 3) oscillations. Phase space reconstruction allowed attractor identification and the computation of a time series complexity measure—the permutation entropy. The entropy measure was found to be able to distinguish between a periodic oscillation associated with a limit cycle attractor, a quasiperiodic oscillation associated with a torus attractor and nonperiodic oscillations associated with higher-dimensional attractors. Importantly, the permutation entropy was able to rank the oscillations, thereby providing an objective index of nystagmus complexity (range 0.15–0.21) that could not be obtained via unstable periodic orbit analysis or attractor identification alone. These results suggest that our framework provides a comprehensive methodology for characterising nystagmus, aiding differential diagnosis and also permitting investigation of the waveforms over time, thereby facilitating the quantification of future therapeutic managements. In addition, permutation entropy could provide an additional tool for future oculomotor modelling.

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“…But based on the data we recorded, the method adjustments are considered reasonable. An updated version of the method has recently been developed (Dunn et al, 2018). This method may further improve the accuracy of the algorithm.…”

Section: Discussionmentioning

confidence: 99%

A robust method for calibration of eye tracking data recorded during nystagmus

et al. 2019

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Eye tracking is a useful tool when studying the oscillatory eye movements associated with nystagmus. However, this oscillatory nature of nystagmus is problematic during calibration since it introduces uncertainty about where the person is actually looking. This renders comparisons between separate recordings unreliable. Still, the influence of the calibration protocol on eye movement data from people with nystagmus has not been thoroughly investigated. In this work, we propose a calibration method using Procrustes analysis in combination with an outlier correction algorithm, which is based on a model of the calibration data and on the geometry of the experimental setup. The proposed method is compared to previously used calibration polynomials in terms of accuracy, calibration plane distortion and waveform robustness. Six recordings of calibration data, validation data and optokinetic nystagmus data from people with nystagmus and seven recordings from a control group were included in the study. Fixation errors during the recording of calibration data from the healthy participants were introduced, simulating fixation errors caused by the oscillatory movements found in nystagmus data. The outlier correction algorithm improved the accuracy for all tested calibration methods. The accuracy and calibration plane distortion performance of the Procrustes analysis calibration method were similar to the top performing mapping functions for the simulated fixation errors. The performance in terms of waveform robustness was superior for the Procrustes analysis calibration compared to the other calibration methods. The overall performance of the Procrustes calibration methods was best for the datasets containing errors during the calibration.

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An automated segmentation approach to calibrating infantile nystagmus waveforms

Cited by 13 publications

References 24 publications

Successful visually guided eye movements following sight restoration after congenital cataracts

Successful visually guided eye movements following sight restoration after congenital cataracts

Analysing nystagmus waveforms: a computational framework

A robust method for calibration of eye tracking data recorded during nystagmus

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