You know, the thing that gives X-rays their ability to penetrate flesh is that they don't interact much with standard electron orbitals. Which means of course they can't interact with the back of the eye, either, so you can't see 'em. Not that X-rays are as common as ordinary light, anyway, or we'd have problems!
Anyway, however she claims to do it, I saw this documentary about this girl, or one like it. Her final assessment wasn't any more successful than someone just guessing. Yes, only 4 out of 7. I could probably do the same.