So I've used fabric before for my kevin mask costume, the problem was it made my vision so limited I had to take the mask off most the time so I could see well anything. I was wondering if any one had any idea's on making coloured eyes in a mask?

Batman is a great example of what I mean. he has white eyes holes in all the comics.

When doing fur-heads, I make most of the eye opaque, but any bits that are black I cut out and then cover the back with about 4 layers of dress netting. Visibility out is not too bad, visibility in is not good, so no one can see you looking out. I imagine other colours of netting will work equally well.

Or you could try taking the lenses off a pair of mirrored sunglasses?

Maybe you can buy like adhesive material for it, maybe something similar to tinted windows?
I'm not sure, but I know I'd try a car shop or internet search if it was me!

the netting was basicly what i used before maybe mine was too thick though. thanks both of you for your idea's I'll have a fiddle and see what i come up with

yes, I think mesh/netting is a good way to do this. Up close to your eyes you should be able to see through, but they can give quite a solid colour look to those who are further away from it.

i used normal shop bought tights to block out my eyes for the witch king's crown. just don't be dumb like me and try to superglue them in place the day you're wearing the thing... superglue takes ages to fully evaporate and it stings your eyes untill is has