vernier acuity

noun
ver·​ni·​er acuity | \ ˈvər-nē-ər- How to pronounce vernier acuity (audio) \

Medical Definition of vernier acuity

: the aspect of visual acuity that involves the ability to detect the alignment or lack of alignment of the two parts of a broken line (as in reading a vernier scale) — compare grating acuity, hyperacuity, stereoacuity