Is there really so called Perfect vision since 20/20 is considered normal vision!

Is there really so called Perfect vision since 20/20 is considered normal vision?

I mean there might be people with very good miraculous vision, better than 20/15 and 20/10, as such is it correct when someone said 20/10 is perfect vision, or should it be termed as excellent vision?

Btw : 20/200 is denoted as legal blindness in America, generally what can they see compared to normal person? (with and without glass)

20/20 distant vision is considered normal vision. It is not perfect, it just means that corrective lenses or surgery would not be needed in everyday situations. There are limits to the visual acuity of the human eye. Humans are generally thought of not having visual acuity better than about 20/16, although there are probably exceptions. I once read that Ted Williams may have had 20/10 vision and explains why he was such a great hitter in baseball. Better than 20/20 would be excellent vision. Hawks have much better visual acuity than humans due to the large number of cones in their eyes. On the Snellen scale they would probably rate a 20/2.

In addition to distant visual acuity there is accommodation (the ability to focus on both distant objects and close objects). A teenager can accommodate about 14 diopters, which allow that person to focus as close as about 3 inches. The crystalline lens is made more convex (like a magnifying glass or thicker in the middle) when focusing close. When humans reach about 45 years, the lens in the eye continues to grow but the surrounding part of the eye stays the same, so the muscle used to push the lens into more of a convex shape doesn't have as much power. At about 45 years old, there is only about 4 diopters accommodation, resulting in only being able to focus as close as 10 inches. At 50 years old it typically is down to 2 diopters and 20 inches, unfortunately about 6 inches beyond normal reading range.

There are people with a slightly longer than usual eyeball from front to back. This is called myopia or difficulty seeing distant objects The opposite is true for people with a slightly shorter than usual eyeball and is called hyperopia, or diffuculty seeing close. Myopes tend to notice the onset of presbyopia later because they have a built-in reading prescription.

A person is considered LEGALLY blind when the best corrected visual acuity is 20/200, or the person's visual field is 20 degrees or less (normal field is 180 degrees). It is not true that all blind persons have absolutely no sight; in fact, most blind persons have some remaining vision. A person may be considered blind when he/she can no longer drive safely, has difficulty reading a newspaper, or cannot see objects to the side.