What makes up our field of vision?

A person's field of vision is normally about 180 degrees, i.e. a semicircle. 1–2% of the field of vision consists of what is called central vision, or also called direct vision. It is this part that you see sharply, for example what is written on a sign. Peripheral vision is the part of the field of vision that is outside central vision and makes up the remaining 98–99% that we cannot perceive or see as well. This is exacerbated when we are tired or under the influence of alcohol.

We can detect things with peripheral vision, but we have to use central vision to be able to see clearly what it is. Imagine that you focus on one point (central vision). Everything else that you don't have in focus is peripheral vision and it's not as sharp as your central vision.