Matt Dunn is a registered Optometrist and is in his third and final year as a post graduate student at Cardiff University. His course include Psychophysics and neurocybernetics in infantile nystagmus and also clinical supervisor for taught courses in orthoptics and optometric clinical practice.
ECEM 2013 - Involuntary saccade initiation is related to the timing of voluntary saccades in infantile nystagmus
Infantile nystagmus, a constant repetitive oscillation of the eyes, has in recent years been found to be influenced by psychological factors, such as visual ‘effort’ and emotional engagement. Our analysis of nystagmus during a conscious visual task reveals a direct relationship between the timing of voluntary saccades and the initiation of the quick phases of nystagmus.
Nineteen subjects with horizontal infantile nystagmus underwent high-speed eye tracking whilst performing saccades to vertically displaced targets. Saccade detection algorithms were applied in both the horizontal and vertical axes to determine the timing of voluntary (vertical) saccades with respect to the involuntary (horizontal) quick phases of nystagmus.
Eye trace analysis reveals that quick phases in the horizontal axis either occur in synchrony with vertical saccades, or are ‘skipped’ altogether (the quick phase is apparently suppressed by the voluntary saccade).
These results show direct modification of the nystagmus waveform in response to a saccadic task, providing evidence that infantile nystagmus is influenced by the voluntary saccadic control system.
Click on image to view a PDF of the poster.