Vernier acuity measures the ability to detect a misalignment or positional offset between visual stimuli. for example between two vertical lines when reading a vernier scale. It is considered a form of visual hyperacuity due to its detectable thresholds being considerably smaller than the diameter of a foveal cone receptor. which limits the spatial resolution of classical visual acuity. https://www.roneverhart.com/Medline-ReNewal-Reprocessed-Arthrex-Scorpion-Needle-AR-13995N-MULTIFIRE-SCORPION-NDL-BLACK-AR13995NR/