Visual Acuity

A measure of the sharpness or clarity of vision, typically expressed as a fraction (e.g., 20/20) or percentage indicating the smallest detail a person can resolve at a standard distance. Visual acuity is one of the primary metrics used to classify the degree of visual impairment, with legal blindness typically defined as 20/200 or worse in the better eye with best correction. However, visual acuity alone does not capture the full picture of functional vision—factors like visual field, contrast sensitivity, color vision, and glare sensitivity also significantly affect a person's ability to perform visual tasks.