What does peripheral vision mean?

Peripheral vision is the part of the field of vision that is outside the central vision, i.e. the part that you see sharply.

• Central vision: Also called direct vision. Makes up 1–2% of the field of view that you can see most clearly. Thanks to central vision, we can perceive what is written on a sign by the road, such as an additional board.
• Peripheral vision: 98–99% of the field of vision that we cannot perceive as clearly as central vision. This is exacerbated when we are tired or under the influence of alcohol. We can detect things with peripheral vision, but must use direct vision to be able to clearly see what it is. Imagine that you are focusing on one point (live vision). Everything else that you don't have in focus is peripheral vision and it's not as sharp as your direct vision. See picture, the grey surface constitutes peripheral vision while the red constitutes direct vision in the human eye.