Blurry Vision

I have found recently, that when playing first person shooters, specifically CS:GO I blur my vision when in the heat of the situation, for instance multiple enemies I'll be clear as day on the first then blur my vision for the rest.. I have no idea why I do this does anyone else?

I play 4:3 on a 16:9 monitor with black-bars ~ 10" away from my eyes. However, I have always played like this, especially back in the day when I took source seriously.

Graphic settings are pretty low for preference and I average ~ 3-600fps generally, but sometimes limit it to 120.

Ambient lighting is dark, but I have two screens providing light.

If anyone does this or knows how to stop themselves doing it, that would be great!

 

eyes