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KMID : 1159320130150030253
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Korean Journal of Vision Science
2013 Volume.15 No. 3 p.253 ~ p.262
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A Correlation Between Horizontal Fixation Disparity and Stereopsis at Close Range
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Yoon Min-Hwa
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Abstract
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Purpose: To investigate a correlation between horizontal fixation disparity and stereopsis by analyzing distribution of types of horizontal fixation disparity. Methods: In this study, stereotest partly using random dot was used in stereopsis tests. We measured horizontal fixation disparity in close proximity through measurement of prism base direction and the amount when two thin lines, one for one eye looks, become overlapped as a line by adding into prism with Wesson fixation disparity card while maintaining a distance of 25 cm from patients. Results: In the types of near horizontal fixation disparity curve, targeting 43 people, the type I was the most distributed to 55.56%, type II of 3.7% is the least, the type III and type IV were distributed to 22.22% and 18.22%. The result of a correlation analysis, which shows the degree of linear correlation between two variables, represented that stereopsis is hardly correlated with Y-intercept(r=-0.17) indicated horizontal fixation disparity, associated phoria(r=-0.13) and disassociated phoria(r=0.02), but it was not statistically significant (p>0.05). Fixation disparity slope of horizontal fixation disparity(r=0.29) was shown to have a low correlation with stereopsis, and it also shows a meaningful statistically result(p<0.05). The Y-intercept indicated horizontal fixation disparity was not nearly associated with fixation disparity slope of horizontal fixation disparity(r=0.12), and it is also not statistically significant (p>0.05). However, a high correlation is founded in between associated phoria(r=0.85) and disassociated phoria(r=-0.43). It proved that the horizontal fixation disparity and phoria was shown they are correlated each other(p<0.05). As a result of regression analysis, the stereopsis was changed as 1.86" if horizontal fixation disparity changes as 1" and the horizontal fixation disparity was changed as 0.04’ if stereopsis changes as 1’. It was statistically significant(p<0.05). Conclusions: This study says there is a low correlation between stereopsis and horizontal fixation disparity and it is difficult to determine stereopsis only using horizontal fixation disparity. Therefore, it is considered other factors above horizontal fixation disparity have greater influence on stereopsis.
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KEYWORD
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Horizontal fixation disparity, Fixation disparity slope of horizontal fixation disparity, Horizontal fixation disparity types, Stereopsis
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