The Study of Distance and Near AC/A Ratio by Stimulus

조절자극 방식에 따른 원거리와 근거리 AC/A비에 관한 연구

  • Jo, Tae-Sik (Department of Optometry, Chodang University) ;
  • Kim, In-Suk (Department of Optometry, Chodang University) ;
  • Jang, Jung-Un (Department of Optometry, Chodang University)
  • Received : 2011.10.26
  • Accepted : 2011.12.17
  • Published : 2011.12.31

Abstract

Purpose: This study was to investigate that near gradient AC/A ratio could be used to prescribe a patient with distance exophoria, we compared the difference between distance gradient AC/A ratio and near gradient AC/A ratio. Also, this thesis was to understand the relationship between calculated AC/A ratio and gradient AC/A ratio. Methods: Objective and subjective refractive error were corrected and we used Howell (3 m) chart for distance phoria tests and Howell-Kim (40 cm) chart for near phoria tests. The near gradient AC/A ratio and calculated AC/A ratio were used by Howell-Kim (40 cm) combined with +1.00 D, -1.00 D, +2.00 D and -2.00 D. Results: The average value of distance exophoria was 1.17${\pm}$1.17 $\Delta$, and the average value of near exophoria was 3.71${\pm}$2.80 $\Delta$ (t-test. p<0.001). The correlation of distance phoria with near phoria was little higher (r = 0.59, p < 0.001). Gradient AC/A ratios depending on measuring distance and stimulus were higher (r = 0.11~0.53. P < 0.001), when distance was shorter and stimulus to accommodation was more. Also, stimulus to accommodation by plus lens was higher than stimulus to accommodation by minus lens (paired t-test. p < 0.001). There was negative correlation between calculated AC/A ratio and gradient AC/A ratio. As the calculated AC/A ratio was higher, gradient AC/A ratio was lesser. Near gradient AC/A ratio was slightly higher than distance gradient AC/A ratio. Distance and near gradient AC/A ratio taken through the subjective -1.00 D were 1.30 $\Delta$/D and 1.68 $\Delta$/D(t-test. t=1.67, p < 0.001). Conclusions: There is negative correlation between calculated AC/A ratio and gradient AC/A ratio. Also, there is subtle difference between near gradient AC/A ratio and distance gradient AC/A ratio. Therefore, we need to measure distance gradient AC/A ratio when a practitioner prescribe glasses for a patient with distance exophoria.

목적: 본 연구는 근거리 경사 AC/A 비가 원거리 외사위 교정에 적용될 수 있는지를 알아 보기 위하여 원거리 및 근거리 경사 AC/A 비의 차이를 비교하고 또한 계산 AC/A 비와 경사 AC/A 비의 관계에 대하여 연구 하였다. 방법: 타각적 및 자각적 굴절검사에 의한 완전교정 후 원거리 경사 AC/A 비 검사는 -1.00 D를 가입한 후 Howell 시표(3 m용)를 사용하였으며, 근거리 경사 AC/A 비 검사는 +1.00 D, -1.00 D, +2.00 D와 -2.00 D를 각각 가입한 후 Howell-Kim(40 cm 용) 시표를 사용하여 사위검사와 계산 AC/A 비를 측정하였다. 결과: 원거리 사위는 평균 외사위 1.17${\pm}$1.17 $\Delta$, 근거리 평균 외사위 3.71${\pm}$2.80 $\Delta$으로 나타나(t-test. p < 0.001), 원근거리 사위의 상관관계(r = 0.59, p < 0.001)는 비교적 높게 나타났다. 경사 AC/A 비는 측정거리와 조절자극에 따라 다양하였고(r = 0.11~0.53. p < 0.001) 측정거리가 가까울수록 조절자극이 클수록 높았다. 또한 플러스 굴절력보다 마이너스 굴절력에 의한 조절자극이 높게 나타났다(t-test. p<0.001). 또한 계산 AC/A 비가 클수록 경사 AC/A 비는 오히려 낮아지는 음의 상관관계를 보였다. 원거리와 근거리에서 -1.00 D 부가한 경사 AC/A 비는 원거리가 1.30 $\Delta$/D 근거리가 1.68 $\Delta$/D로 근거리 AC/A 비가 유의적인 수준에서 약간 크게 나타났다(t-test. t=1.67, p<0.001). 결론: 본 연구를 통하여 계산 AC/A 비와 경사 AC/A 비의 음의 상관관계를 알 수 있었고, 근거리 경사 AC/A 비가 원거리 경사 AC/A 비보다 작지만 유의적 수준의 차이를 보여 원거리 외사위의 교정은 원거리 경사 AC/A비를 반드시 측정할 필요성이 있음을 알 수 있었다.

Keywords

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