Reflexive Optokinetic Nystagmus in Younger and Older Observers under Photopic and Mesopic Viewing Conditions
Author(s)
Hine, Trevor J
Wallis, Guy
Wood, Joanne M
Stavrou, Efty P
Griffith University Author(s)
Year published
2006
Metadata
Show full item recordAbstract
PURPOSE. To investigate the effect of age on optokinetic nystagmus (OKN) in response to stimuli designed to preferentially stimulate the M-pathway. METHOD. OKN was recorded in 10 younger (32.3 ᠵ.98 years) and 10 older (65.6 ᠶ.53) subjects with normal vision. Vertical gratings of 0.43 or 1.08 cpd drifting at 5௳ or 20௳ and presented at either 8% or 80% contrast were displayed on a large screen as full-field stimulation, central stimulation within a central Gaussian-blurred window of 15ࠤiameter, or peripheral stimulation outside this window. All conditions apart from the high-contrast condition were presented in a random ...
View more >PURPOSE. To investigate the effect of age on optokinetic nystagmus (OKN) in response to stimuli designed to preferentially stimulate the M-pathway. METHOD. OKN was recorded in 10 younger (32.3 ᠵ.98 years) and 10 older (65.6 ᠶ.53) subjects with normal vision. Vertical gratings of 0.43 or 1.08 cpd drifting at 5௳ or 20௳ and presented at either 8% or 80% contrast were displayed on a large screen as full-field stimulation, central stimulation within a central Gaussian-blurred window of 15ࠤiameter, or peripheral stimulation outside this window. All conditions apart from the high-contrast condition were presented in a random order at two light levels, mesopic (1.8 cdm-2) and photopic (71.5 cdm-2). RESULTS. Partial-field data indicated that central stimulation, mesopic light levels, and lower temporal frequency each significantly increased slow-phase velocity (SPV). Although there was no overall difference between groups for partial-field stimulation, full-field stimulation, or low-contrast stimulation, a change in illumination revealed a significant interaction with age: there was a larger decrease in SPV going from photopic to mesopic conditions for the older group than the younger group, especially for higher temporal frequency stimulation. CONCLUSIONS. OKN becomes reflexive in conditions conducive to M-pathway stimulation, and this rOKN response is significantly diminished in older healthy adults than in younger healthy adults, indicative of decreased M-pathway sensitivity.
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View more >PURPOSE. To investigate the effect of age on optokinetic nystagmus (OKN) in response to stimuli designed to preferentially stimulate the M-pathway. METHOD. OKN was recorded in 10 younger (32.3 ᠵ.98 years) and 10 older (65.6 ᠶ.53) subjects with normal vision. Vertical gratings of 0.43 or 1.08 cpd drifting at 5௳ or 20௳ and presented at either 8% or 80% contrast were displayed on a large screen as full-field stimulation, central stimulation within a central Gaussian-blurred window of 15ࠤiameter, or peripheral stimulation outside this window. All conditions apart from the high-contrast condition were presented in a random order at two light levels, mesopic (1.8 cdm-2) and photopic (71.5 cdm-2). RESULTS. Partial-field data indicated that central stimulation, mesopic light levels, and lower temporal frequency each significantly increased slow-phase velocity (SPV). Although there was no overall difference between groups for partial-field stimulation, full-field stimulation, or low-contrast stimulation, a change in illumination revealed a significant interaction with age: there was a larger decrease in SPV going from photopic to mesopic conditions for the older group than the younger group, especially for higher temporal frequency stimulation. CONCLUSIONS. OKN becomes reflexive in conditions conducive to M-pathway stimulation, and this rOKN response is significantly diminished in older healthy adults than in younger healthy adults, indicative of decreased M-pathway sensitivity.
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Journal Title
Investigative Ophthalmology and Visual Science
Volume
47
Issue
12
Copyright Statement
© 2006 Association for Research in Vision and Ophthalmology. Self-archiving of the author-manuscript version is not yet supported by this publisher. Please refer to the journal link for access to the definitive, published version or contact the author for more information.
Subject
Biological sciences
Biomedical and clinical sciences