So does your survivor really perform self-surgery by carving out it’s eyes with a butcher knife and a medkit or are CBMs equipped with some sort of surgery assistance function that make them able to more or less install themselves as long as you know how to opperate them ?
Officially, CBMs are significantly “self-installing” - that is, yes, you need position correctly and a few other things, but the actual cutting and such they do themselves.
Personally, I think that salvaged CBMs (what you get from a corpse) should require some kind of additional parts (which you could save from ones you’ve already installed, perhaps). Also, there should be facilities where people get them installed that have dedicated machinery for the purpose.