There is a saying “hindsight is 20/20 vision”. Simply put it is easy to know the right thing to do looking back, suggesting that hindsight is 20/20 or perfect vision. But what does 20/20 vision really mean?
A 20/20 score on an eye chart test simply means you can see at 20 feet what you ‘should’ be able to see at that distance. In other words your vision is ‘normal’ with the majority of people in the population being able to see what you see at 20 feet. (In metric, the standard is 6 meters and it’s called 6/6 vision).
Having 20/20 vision does not necessarily mean you have perfect vision. 20/20 vision only indicates the sharpness or clarity of vision at a distance. Overall vision includes peripheral awareness or side vision, eye coordination, depth perception, focusing ability and colour vision.
However, if your vision is weaker, say 20/40, this means that the line you correctly read at 20 feet could be read by a person with normal vision at 40 feet. Visual acuity of less than 20/200 constitutes legal blindness in South Africa.
Eyes like a hawk…
Hawks, owls and other birds of prey have much sharper vision than humans. For example, a hawk might have 20/2 vision, seeing at 20 feet what we would only be able to see at two feet. A hawk has a much smaller eye than a human being but has lots of sensors (cones) packed into that space, giving a hawk vision that may be eight times more acute than that of a human’s.
Don’t take your eyes for granted. We may not have a hawk’s visual acuity but there are things we can do to maintain good eye health. Protect your sight with these six tips from WebMD.