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Quantifying perception and oculomotor instability in infantile nystagmus

Dunn, Matthew 2014. Quantifying perception and oculomotor instability in infantile nystagmus. PhD Thesis, Cardiff University.
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Abstract

The purpose of the studies described herein was to better understand the impact of involuntary eye movements on oculomotor control and perception in infantile nystagmus. Therapeutic interventions that result in slowed nystagmus oscillations often fail to elicit significant quantifiable improvements in visual function, despite patients reporting subjective benefits. It is difficult to justify surgical or pharmacological intervention when the only outcome measures are subjective. Objective quantification of nystagmus eye movements per se usually involves time-consuming manual marking of recordings to both calibrate and analyse data. As a result, analyses are rarely (if ever) performed in the clinical setting. Software was therefore developed to automate calibration and assessment. Psychophysical experiments were undertaken to quantify the spatiotemporal constraints of vision in infantile nystagmus. Visual acuity was measured in the absence of retinal image motion to reveal the maximum improvement to spatial vision that might be expected if nystagmus were halted altogether. The results indicate that poor spatial vision underlies infantile nystagmus, even in cases without comorbid pathology. Gaze acquisition time was compared to stimulus recognition time. The results indicate that infantile nystagmus does not increase visual processing time; rather, redeploying gaze takes longer. An incidental finding revealed a temporal relationship between voluntary saccades and involuntary nystagmus quick phases. Both typically occur together, presumably to maximise efficiency and minimise saccadic suppression. Clinical tests of gaze acquisition time must now be developed, to be used in conjunction with the software developed here, as objective outcome measures of therapeutic interventions.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Optometry and Vision Sciences
Subjects: R Medicine > RE Ophthalmology
Uncontrolled Keywords: nystagmus; perception; oculomotor; psychophysics
Last Modified: 05 Jun 2017 04:29
URI: http://orca.cf.ac.uk/id/eprint/59972

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