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KMID : 1159320150170040471
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Korean Journal of Vision Science
2015 Volume.17 No. 4 p.471 ~ p.480
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Comparison between Gradient AC/A Ratio and Response AC/A Ratio by Additional Spherical Powers
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Lee Se-Hee
Yu Dong-Sik
Son Jeong-Sik
Kim Ki-Hong
Roh Byeong-Ho
Kwak Ho-Wen
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Abstract
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Purpose: This study was to investigate stimulus (±)AC/A ratio, response (±)AC/A and general gradient AC/A ratio according to additional spherical powers in phoria groups. Then, these AC/A ratios were compared at each phoria
Methods: Using the open-field autorefractometer (Nvision-K 5001) and modified Thorington method(MIM card, Muscle Imbalance Measure card) at 40cm fixation distance to 85 persons with average 20.72±1.78 ages, the accommodative responses and the near horizontal phorias were measured by changing accommodative stimulus through additional lenses at the binocular vision.
Results: When the stimulus (±)AC/A ratio and the general gradient AC/A ratio were compared, In exophoria group, the stimulus (-)AC/A ratio were greater than general gradient AC/A ratio at (-) additional lenses. In esophoria group, the stimulus (+)AC/A ratio had greater than general gradient AC/A ratio at (+) additional lenses. But the differences had not significant differences statistically. As a result of analyzing general gradient AC/A ratio and response (±)AC/A ratio by using the additional lenses, exophoria group had more differences of general gradient AC/A ratio and response (-)AC/A ratio at -0.50D, -1.00D, -1.50D, -2.00D addition lens (p<0.05). esophoria group had more differences at +0.50D, +1.00D, +1.50D, +2.00D addition lens (p<0.05). These were significant differences statistically. When response (+)AC/A and response (-)AC/A ratio were compared by the repeated measurement ANOVA, In exophoria group and esophoria group, the differences of (-)AC/A ratio at accommodative stimulus by (-) addition lens and response (+)AC/A ratio at accommodative relaxation by (+) addition lens had significant differences statistically.
Conclusions: Accommodative convergence was shown effective changes with (-) lens stimulus in exophoria and with (+) lens stimulus in esophoria. Therefore, when the abnormal binocular vision was prescribed in the clinical trials, it is necessary to apply response (+), (-)AC/A ratio rather than general gradient AC/A ratio.
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KEYWORD
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Accommodative response, Near horizontal phoria, Stimulus (±)AC/A ratio, Response (±)AC/A ratio, Gradient AC/A ratio
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