There are multiple "bionic eye" items which could be good for a cyclops. I haven't tested whether they make a cyclops immune to blindness or not, but usually they cause a "lost an eye" affliction, unless you've already lost an eye. I have used them on commanders who had lost an eye in Dominions I, since it wouldn't do them any more harm. I never saw such a commander suffer the "lost the other eye" affliction, but I wasn't trying...
It'd be interesting if such eyes could cure blindness, but would also have a chance to be destroyed on subsequent eye hits. For all I know, that's how it works...
PvK