關於AC/A比之proximal vergence

AC/A目的在了解患者每調節或放鬆一個定量的調節量時，可以改變或帶動多少稜鏡單位的內聚或開散量。AC/A比於臨床分析驗光檢查資料中扮演重要的角色，同時在決定最後配鏡處方時也具有獨特的功能。

proximal vergence 在gradient AC/A及calculated AC/A間的作用

To estimate proximal vergence clinically

PD60mm

Distance phoria = 4 eso

Near phoria = 10 eso

Phoria through +1.00 at near = 5 eso 

gradient AC/A=5△/D

calculated AC/A=8.4△/D

proximal vergence=8.5.

The calculated AC/A ratio is usually larger than the gradient AC/A because of the effect of proximal vergence and the lag of accommodation.