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?
yeah, definitely makes it hard to see. It changes the way the light is focused onto the retina. My eyes are pretty aawesome!
You are so lucky. I am nearsighted, so whenever I take my glasses off, I'm practically blind.
the shape of the eyeball or the cornea, and reduced flexibility of the lens. Too high or too low refractive error (in relation to the length of the eyeball) is the cause of nearsightedness (myopia) or farsightedness (hyperopia) (normal refractive status is referred to as emmetropia). Other optical causes are astigmatism or more complex corneal irregularities. These anomalies can mostly be corrected by optical means (such as eyeglasses, contact lenses, laser surgery, etc.).
Neural factors that limit acuity are located
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 "