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KMID : 1011420200250010041
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Journal of Korean Ophthalmic Optics Society
2020 Volume.25 No. 1 p.41 ~ p.54
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Correlation between Convergence Functional Changes and SubjectiveSymptoms after Near Work in a Virtual Walking Condition
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Jung Won-Young
Lee Da-Gyo
Jeong Ju-Hee
Park Mi-Jung
Kim So-Ra
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Abstract
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Purpose: In this study, the change in convergence function and its correlation with subjective symptoms after participants watched a movie in a virtual walking environment with vertical movements were investigated.
Methods: A smartpad, which was made to move repeatedly in the vertical direction, was set as near work in a virtual walking condition, and 50 men and women in their 20s were asked to watch a movie for 30 minutes. Measurements of near point of convergence, near heterophoria, and horizontal and vertical fusional vergences before and after the subjects watched the movie were taken to determine the change in convergence function, and the correlation between the convergence functional change and subjective symptoms was further analyzed using a survey of general and eye-related subjective symptoms according to the subjects’ near heterophoric values.
Results: In the virtual walking condition, the near point of convergence tended to recede after subjects watched the movie compared with the value before watching the movie; however, a statistically significant change was found only in subjects whose near heterophoric values were within the range of orthophoria. Near heterophoria showed a tendency of orthophoric shifts on average even though most subjects showed an exophoric shift. Meanwhile, horizontal and vertical fusional vergences showed different changing patterns depending on the range of the subjects’ near heterophoric values. That is, the changes in horizontal fusional convergence that occurred after watching the movie were correlated with general subjective symptoms; however, the changes in vertical fusional vergence showed different correlations with eye-related subjective symptoms depending on the range of the subjects’ near heterophoric values.
Conclusions: This study showed that passive near work in a virtual walking condition with regular movement in the vertical direction caused overall changes in convergence function and that changes in horizontal fusional vergence were correlated with general subjective symptoms according to subjects’ near heterophoric values prior to near work. Therefore, it is suggested that near hetorophoric values should be considered in eyeglass prescriptions to reduce the changes in convergence function and fatigue when conducting near work in a dynamic environment.
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KEYWORD
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Virtual walking condition, Near point of convergence, Horizontal fusional vergence, Vertical fusional vergence, Subjective symptoms
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