I just released my Eye Texture on blendswap it comes with a .xcf, This is a highly versatile eye texture and I release the work under CC0 (information here), my gift from me to you. enjoy -proxe
you can download at BlendSwap
or you can direct download here (blendswap file size is smaller)
the actual .xcf is 1024x1024, here is an example:
In the .xcf there is a total of 15 layers that you can color & mix to your needs.