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KMID : 1159320150170030311
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Korean Journal of Vision Science
2015 Volume.17 No. 3 p.311 ~ p.320
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The Comparison of the subjective associated phoria at near and distance by fixation disparity test charts
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Kim Hyun-Il
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Abstract
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Purpose: This study was intended to compare the subjective horizontal and vertical associated phoria at near and distance measured using the Pointer test, Mallett test, Chart Projector cross test(with a central fusion lock).
Method: The subjective horizontal and vertical associated phoria at near and distance was measured using the Pointer test, Mallett test, Chart Projector cross test(with a central fusion lock) in 19 subjects who experience eye strain when reading text or perform near work and were selected on the basis of normal accommodative function.
Results: Subjective horizontal associated phoria at distance measured using the Chart Projector cross test(with a central fusion lock), Mallett test, Pointer test were ?0.62±0.27△, -0.32±0.23△, -0.44±0.22△ respectively and there were statistically significant difference between tests(F=7.321, p=0.002). Subjective vertical associated phoria at distance measured using the Chart Projector cross test(with a central fusion lock), Mallett test, Pointer test were ?0.10±0.11△, -0.09±0.12△, -0.12± 0.11△ respectively and there were no statistically significant difference between tests(F=0381,
p=0.685). Subjective horizontal associated phoria at near measured using the Mallett test and Pointer test were -0.36±0.30△, ?0.50±0.31△ respectively and there were statistically significant difference between tests(t=-2.625, p=0.017). Subjective vertical associated phoria at near measured using the Mallett test and Pointer test were ?0.08±0.12△, ?0.10±0.11△ respectively and there were statistically significant difference between tests(t=-2.191, p=0.042).
Conclusion: In this study, subjective horizontal associated phoria at distance showed the most exo FD findings when determined using the chart projector cross test, which has a weaker central and peripheral fusion stimulus than that of the Mallett test and Pointer test, also in the distance Mallett test and Pointer test showed more exo FD findings when determined using the Pointer test, which has a larger vertical gap between two nonius lines than that of the Mallett test. Subjective vertical associated phoria at distance showed the same tendency as horizontal at distance. Subjective
horizontal associated phoria at near in the Mallett test and Pointer test showed the same tendency as horizontal and vertical at distance. Therefore, when subjective horizontal associated phoria at near and distance is measured using a device with different designs each other, it is important to understand a constituting principle of fixation disparity test charts because the size and location of central and peripheral fusion locks, gap between the fixation point and the nonius line, length of nonius line, etc. have an effect on the results of the test.
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KEYWORD
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Fixation disparity, Pola test, Pointer test, Mallett test, Chart projector cross test
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