|I have a glass eye.|
You wouldn't know if I hadn't told you. It's attached to my muscles and tendons, just like my old biological eye that it replaced and its twin that still lives in my head. It moves just like my old eye and its twin. It's also fitted with a camera, which is wired to my visual cortex.
I can see from my glass eye and its biological twin. The only problem is interference. Sometimes my glass eye picks up newscasts, cartoons, or home videos.