acuity

详细解释:n. 尖锐, (疾病的)剧烈, 敏锐
【化】 锐度; 分辨能力
【医】 敏度

英语解释：

名词 acuity:

sharpness of vision; the visual ability to resolve fine detail (usually measured by a Snellen chart)同义词：visual acuity, sharp-sightedness