Visual acuity is the ability to perceive and differentiate two separate stimuli at a certain angle, that is, the ability to spatial resolution of the visual system. It can also be defined as the ability to detect an object in a field of vision (minimum visible), the ability to separate two elements (minimum separable) and the ability to name a symbol or its position (minimum recognizable).
Normal visual acuity in an adult is 1 (6/6), but there are very few people who are able to reach 2. What is curious is that when we are born, the visual system is very immature and a newborn baby only looks at 0.05, 2 months at 0.15, at 6 months at 0.40, at a year and a half at 0.50, at two years at 0.65 and at 3 years at 1.
Visual acuity is the characteristic of the vision that is most noticeable when there are graduation problems in the eyes.