Compute the accommodative convergence to accommodation (AC/A) ratio from prism and fixation tests.
梯度法用加镜前后隐斜差除以镜片度;计算法以瞳距加上隐斜差除以调节需求(100/近距cm)求得每屈光度引发的集合量(Δ/D)。
| AC/A (Δ/D) | 类型 | 表现 | 处理 |
|---|---|---|---|
| 3-5 | 正常 | 调节-集合协调 | 无需处理 |
| <3 | 低AC/A | 集合不足,外隐斜 | 集合训练/BI棱镜 |
| >6 | 高AC/A | 集合过强,内隐斜 | 下加光/BO棱镜 |
| >8 | 显著高AC/A | 调节诱发内斜 | 下加光+视觉训练 |
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Definition of AC/A | AC/A = convergence change (prism dioptres) / accommodation change (dioptres) | Duane A. (1922), Studies in monocular and binocular accommodation, Am. J. Ophthalmol. |
| Two measurement methods | The gradient method changes the accommodative stimulus; the calculated method uses near/far phoria | Duane A. (1922), Studies in monocular and binocular accommodation |
| Typical range | Clinically typical values are about 3-5 Δ/D; extremes relate to asthenopia | Duane A. (1922), Studies in monocular and binocular accommodation |
| Relation to correction | Changing the refractive correction or near addition alters the accommodative stimulus and hence the AC/A | ISO 13666:2019, Ophthalmic optics - Vocabulary |
用梯度法或计算法(隐斜法)计算AC/A比值,评估调节性集合与调节的联动关系。
AC/A比值计算器,用梯度法和计算法(隐斜法)计算调节性集合与调节的比值。。医疗专业工具,基于权威医学标准,仅供参考。
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