Graphic showing acuity of vision in reading (during one eye stop): image by Hans-Werner34, 2008
Around the fixation point only four to five letters are seen with 100% acuity
This frees one from nagging peripheral demands for attention to insignificant details
By turning them into a blur
But narrowness of vision shouldn't be thought of as a disadvantage
When someone urges you to "Stay focused" what they are really saying is
"Concentrate on your fixation"
The Magician: Hieronymus Bosch, 1475-1480 (Musée Municipal, Saint-Germain-en-Laye)