Eyes animation texture problem

I would just change my model sprite eye.(normal to the spiral *** When my character dies)

I do not know the best way to do this.

I put all of model textures together (to decrease drawcalls). I do not want to create a another texture just like with different eye and load both. (I would like to conserve ram).

I'm just trying to use a texture with several UVs, this is the best way? Or what is the best way?