Comment by Levitating

> One variety used rose-colored lenses, as the coloring was thought to prevent a chicken wearing them from recognizing blood on other chickens

So that's only relevant tot the rose-colored variant.

I think the answer lies in this quote right above it:

> They differ from blinders in that they allow the bird to see forward, whereas blinders do not.

Where "blinders" is a hyperlink to an article concerning blinders for chickens.

That article has a piece comparing blinders to spectacles:

> Blinders work by reducing the accuracy of pecking at the feathers or body of another bird, rather than spectacles which have coloured lenses and allow the bird to see forwards but alter the perceived colour, particularly of blood.

But this again only refers to the coloured lenses, which in the article was said to be a variant.

So my understanding is that both blinders and spectacles work by restricting the vision of the bird but the spectactles additionally had a rose-colored variant.