Ocular tremor: Difference between revisions
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== Cause == |
== Cause == |
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Human eyes are constantly moving, even if they appear to be focused on an object.<ref name=":12">{{Citation|last=Alexander|first=Robert G.|title=Fixational Eye Movements|date=2019|url=https://doi.org/10.1007/978-3-030-20085-5_3|work=Eye Movement Research: An Introduction to its Scientific Foundations and Applications|pages=73–115|editor-last=Klein|editor-first=Christoph|series=Studies in Neuroscience, Psychology and Behavioral Economics|place=Cham|publisher=Springer International Publishing|language=en|doi=10.1007/978-3-030-20085-5_3|isbn=978-3-030-20085-5|access-date=2021-11-06|last2=Martinez-Conde|first2=Susana|editor2-last=Ettinger|editor2-first=Ulrich}}</ref> These constant [[Oscillation|oscillations]] are called fixational eye movements, and they include ocular microtremor, [[Microsaccade|microsaccades]], and drift.<ref name=":12" /><ref name=":0">{{Cite journal|last=Alexander|first=Robert G.|last2=Macknik|first2=Stephen L.|last3=Martinez-Conde|first3=Susana|date=2018-03-13|title=Microsaccade Characteristics in Neurological and Ophthalmic Disease|url=http://journal.frontiersin.org/article/10.3389/fneur.2018.00144/full|journal=Frontiers in Neurology|volume=9|pages=144|doi=10.3389/fneur.2018.00144|issn=1664-2295|pmc=PMC5859063|pmid=29593642}}</ref> Ocular tremor is the smallest of these movements, and it often overlaps with drift.<ref name=":12" /><ref name=":0" /> This makes it the most difficult fixational eye movement to measure.<ref name=":12" /><ref name=":0" /> Due to these difficulties in measurement, fewer studies have been performed on ocular microtremor,<ref name=":12" /><ref name=":0" /> leading to the phenomenon of ocular tremor not being well-understood.<ref name=":12" /><ref name=":0" /> |
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Researchers are not entirely sure of the cause of ocular microtremor.<ref name=":12" /> It may be a result from the firing of [[Motor neuron|motor neurons]] at different times.<ref name=":12" /><ref>{{Citation|last=Skalicky|first=Simon E.|title=Neural Control of Eye Movements|date=2016|url=http://link.springer.com/10.1007/978-981-287-846-5_18|work=Ocular and Visual Physiology|pages=251–270|place=Singapore|publisher=Springer Singapore|language=en|doi=10.1007/978-981-287-846-5_18|isbn=978-981-287-845-8|access-date=2021-11-06}}</ref> It has also been suggested that ocular tremor is a result of the eye being balanced between opposing muscles.<ref name=":12" /> |
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== Size and Measurement == |
== Size and Measurement == |
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Revision as of 21:22, 5 December 2021
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Ocular tremor (ocular microtremor) is a constant, involuntary eye tremor of a low amplitude and high frequency. It is a type of fixational eye movement that occurs in all normal people, even when the eye appears still.[1] The frequency of ocular microtremor has been found to range from 30 Hz to 103 Hz, and the amplitude is approximately four thousandths of a degree.[1][2]
Cause
Human eyes are constantly moving, even if they appear to be focused on an object.[3] These constant oscillations are called fixational eye movements, and they include ocular microtremor, microsaccades, and drift.[3][4] Ocular tremor is the smallest of these movements, and it often overlaps with drift.[3][4] This makes it the most difficult fixational eye movement to measure.[3][4] Due to these difficulties in measurement, fewer studies have been performed on ocular microtremor,[3][4] leading to the phenomenon of ocular tremor not being well-understood.[3][4]
Researchers are not entirely sure of the cause of ocular microtremor.[3] It may be a result from the firing of motor neurons at different times.[3][5] It has also been suggested that ocular tremor is a result of the eye being balanced between opposing muscles.[3]
Size and Measurement
See also
References
- ^ a b Alexander, Robert G.; Martinez-Conde, Susana (2019), Klein, Christoph; Ettinger, Ulrich (eds.), "Fixational Eye Movements", Eye Movement Research: An Introduction to its Scientific Foundations and Applications, Studies in Neuroscience, Psychology and Behavioral Economics, Cham: Springer International Publishing, pp. 73–115, doi:10.1007/978-3-030-20085-5_3, ISBN 978-3-030-20085-5, retrieved 2021-11-06
- ^ Shakhnovich, A. R. (1977), "Fixation Movements of the Eyes", The Brain and Regulation of Eye Movement, Boston, MA: Springer US, pp. 23–66, doi:10.1007/978-1-4684-6964-6_2, ISBN 978-1-4684-6966-0, retrieved 2021-11-06
- ^ a b c d e f g h i Alexander, Robert G.; Martinez-Conde, Susana (2019), Klein, Christoph; Ettinger, Ulrich (eds.), "Fixational Eye Movements", Eye Movement Research: An Introduction to its Scientific Foundations and Applications, Studies in Neuroscience, Psychology and Behavioral Economics, Cham: Springer International Publishing, pp. 73–115, doi:10.1007/978-3-030-20085-5_3, ISBN 978-3-030-20085-5, retrieved 2021-11-06
- ^ a b c d e Alexander, Robert G.; Macknik, Stephen L.; Martinez-Conde, Susana (2018-03-13). "Microsaccade Characteristics in Neurological and Ophthalmic Disease". Frontiers in Neurology. 9: 144. doi:10.3389/fneur.2018.00144. ISSN 1664-2295. PMC 5859063. PMID 29593642.
{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link) - ^ Skalicky, Simon E. (2016), "Neural Control of Eye Movements", Ocular and Visual Physiology, Singapore: Springer Singapore, pp. 251–270, doi:10.1007/978-981-287-846-5_18, ISBN 978-981-287-845-8, retrieved 2021-11-06
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