In several shows, there are characters who gain solid black eyes, usually to indicate that they have turned on sort of superhuman or supernatural ability. For instance, Alexander Lyta in Babylon 5
Ruby in Supernatural
And Bizarro Supergirl in Supergirl
(Strangely, this effect seems to be used quite frequently with long-haired women).
How is this effect achieved? My first thought is contacts, but all the contacts I've ever seen aren't big enough to completely cover the eye. Also, wouldn't solid black contact lenses obstruct vision?