I have amazing eyesight! Some people will call it a good visual acuity! 
Lucky! I have horrible eyesight. I have to wear glasses. Does visual acuity mean 20/20 or better?
It just refers to how good or bad the eyesight is. Some people have refractive errors or abnormalities in the shape of their eyeballs.
I'm guessing refractive errors make it harder for them to see? How good is your vision?
Refractive error
Refractive error, also known as refraction error, is a problem with focusing light accurately onto the retina due to the shape of the eye. The most common types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. Near-sightedness results in far away objects being blurry, far-sightedness and presbyopia result in close objects being blurry, astigmatism causes objects to appear stretched out or blurry. Other symptoms may include double vision, headaches, and eye strain.
Near-
Visual perception
Visual perception is the ability to interpret the surrounding environment using light in the visible spectrum reflected by the objects in the environment. This is different from visual acuity, which refers to how clearly a person sees (for example "20/20 vision"). A person can have problems with visual perceptual processing even if he/she has 20/20 vision.
The resulting perception is also known as visual perception, eyesight, sight, or vision (adjectival form: "visual", "optical", or "