| Objective vs subjective measures of fixation disparity for short and long fixation periods. | |
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MedLine Citation:
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PMID: 20629960 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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PURPOSE: Fixation disparity, i.e. the vergence error for stationary fusion stimuli, can be measured objectively with eye trackers and subjectively with nonius lines. Between these two measures, previous studies found differences that tended to be proportional to the amount of forced vergence, i.e. the discrepancy between vergence and accommodative stimulus. We investigate whether objective and subjective fixation disparity might be similar without forced vergence. METHOD: We simultaneously measured fixation disparity with the EyeLink II system and with flashed dichoptic nonius lines in 17 subjects who observed targets at a vergence stimulus of 6 deg in an haploscope with 60 cm viewing distance. RESULTS: We found individual differences in objective fixation disparity in a range of about 20 (eso) to -60 (exo) min arc which was considerably larger than the range of subjective fixation disparity. Results were similar for long fixation periods (about 15 s) and short fixation periods (about 1.5 s) between 5 deg saccadic gaze shifts. Further, objective fixation disparity was correlated with objective heterophoria, i.e. the vergence state without a fusion stimulus (r = 0.8, p < 0.001). CONCLUSION: Subjective fixation disparity explained only about 25% of the inter-individual variability in objective fixation disparity. The discrepancy between these two measures might be explained by sensory shifts in retinal correspondence, also in the present condition without forced vergence. |
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Authors:
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Wolfgang Jaschinski; Stephanie Jainta; Wilhelm Bernhard Kloke |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) Volume: 30 ISSN: 1475-1313 ISO Abbreviation: Ophthalmic Physiol Opt Publication Date: 2010 Jul |
Date Detail:
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Created Date: 2010-07-15 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8208839 Medline TA: Ophthalmic Physiol Opt Country: England |
Other Details:
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Languages: eng Pagination: 379-90 Citation Subset: IM |
Affiliation:
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Leibniz Research Centre for Working Environment and Human Factors, IfADo, Ardeystr. 67, D 44139 Dortmund, Germany. jaschinski@ifado.de |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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