近視屈光度， AC/A比測量方法對AC/A比值影響之研究

The effects of myopia and AC/A measuring methodology on AC/A ratio outcome

Purpose:This study aims (1)to understand the extent of myopia on the AC/A ratio, (2)to examine whether the alculated A C/A ratio would be different fom the gradient AC/A ratio in a clinical setup, (3)to investigate the difference between positive and negative sphericallens stimuli on AC/A ratio, and (4)to unveil the mutual effects of different amounts of myopia and AC/A measuring methodology on AC/A ratlO outcome. Methods:volunteered participants (30 males and 42 females) were refractive examined and divided into two groups : 40 low myopes (- 0.50D< spherical equivalents(SE) < - 3.00D) and 32 high myopes (SE≧- 3.00D). The Von Graefe Technique (VG) was used to measure the distance lateral phoria at 6 m and near lateral phoria at 0.4 m. Binocular additions of positive and negative spherical lenses were used for lateral phoria measurement. The calculated AC/A ratio and the gradient AC/A ratio were then correlated and analyzed by two-way ANOVA. Results: The average AC/A ratios ofthe high myopes were higher than those ofthe low myopes. The average calculated AC/A ratios were higher than the average gradient AC/A ratios. In gradient AC/A ratios, the average value using positive spherical addition was higher than when using negative spherical addítion. No significant difference of AC/A ratios was found between the bi-factorial inter-elations of myopia and AC/A ratio determination methods (F=0.75, P=0.48> 0.05). The extent of myopia did not affect AC/A ratio (F=3.14， P= 0.081> 0.05). There was a significant difference among measuring methods and the outcomes of AC/A ratios (F = 6. 16， P= 0.003< 0.05). The calculated AC/A ratio was significantly different from the gradient AC/A ratio (both P=0.003< 0.005). However, no significant difference was found between the gradient AC/A ratios using positive lenses and those using negative lenses (P=0.46 >0.05). Conclusions:This study shows that the calculated AC/A ratio is significantly greater than the gradient AC/A ratio, probably due to proximal convergence and accommodative lag. A greater amount of myopia has a higher AC/A ratio than that of lower myopia in all AC/A ratio measurement, though the difference was insignificant. This finding suggests that there are deviations between stimulus AC/A ratio and response AC/A ratio. Our data suggest that anomalous binocular factors and accommodative lag should be considered for myopia research, apart from stimulus AC/A ratio. 目的:探索(1)近視度數高低與AC/A比價有無差異，並比較(2)調節性輻轅與調節之比率(AC/A1t)，與計算式AC/A及梯度式AC/A比間整體性的差異，其中包含(3)以正、負球面鏡片刺激調節所產生梯度式AC/A比值之間有無差異性。(4)近視屈光度的高低與AC/A比測量方法兩者有無交互作用的影響。方法: 30名男性及42名女性，共72名參與本研究計畫，經屈光檢查後分成低近視組(-0.50D <等價球面度SE< -3.00D)有40名，及高近視組(等價球面度SE SE~-3.00D)有32名。以Von Graefe Technique(VG)測量斜位的方法及步驟，於距離6M及O .4M測量遠方及近方水平斜位;再分別雙眼同時加入正，負1.00D球面鏡測量其水平斜位。比較分析計算式AC/A比值及梯度式AC/A比值，並以2way-ANOVA1Ja以檢定交互作用影響及差異性。結果:高近視組AC/A平均數均高於低近視組AC泣，計算式AC/A平均數高於梯度式(正球面鏡)AC/A平均數又高於梯度式(負球面鏡)AC/A平均數。近視屈光度及ACIA測量方法影響AC/A比值的交互效果(F = 0.75 'P= 0.48> 0.05)無統計上差異。近視屈光度影響AC/A比值的效果(F = 3.1 4 ' P= 0.081> 0.05)無統計上差異。但不同AC/A測量方法影響AC/A比恆的效果(F = 6.16 ' P= 0.003 < 0.05)具統計上差異，即計算式AC/A與梯度式(正球面鏡)AC/A(P = 0.003 < 0.05)有顯著差異;計算式AC/A與梯度式(負球面鏡)AC/A(P = 0.003 < 0.05)有顯著差異;而梯度式(正球面鏡)AC/A與梯度式(負球面鏡)AC址， (P = 0.46> 0.05)則無顯著差異。結論:結果顯示計算式AC/A大於梯度式ACIA有顯著差異。原因可能為近接性聚合(proximal convergence)及調節遲緩(Accommodation lag)因素所造成差異。高近視AC/A平均數均高於低近視AC/A ·雖然未達顯著性9 但其差異顯示刺激式ACA與反應式ACA不同的影響。本研究建議後續近視相關研究除了刺激式AC/A比之外，尚應考量異常雙眼前見因素及調節遲緩。