Why are operating room walls green?

O. R. linen are green because, green is the opposite of red on the colour wheel. When you stare at any intense colour long enough and then look at a piece of white paper you will see the opposite colour, not the white piece of paper. In the operating room you are looking at blood which is red, when you lift your eyes from the operating field to look at any other surface it would appear to have a green tinge to it, so they paint the walls green, have green gowns, drapes and other linens to make it easier on the eyes. In fact the colour of the linen is called eyerest green.