Eyemaker.

My grandmother has an artificial eye from him and I cannot tell the difference between the real one.

Yes, Ocularists are the hidden gems in this world. According to my ocularist, there are probably less than 60 of them in the US certified. Here in Portland, we have luckily 3 professionals. My first visit to the ocularist was when I was 5 and had my first artificial eye for almost 5 years. Longer than I should have, but we just didn't know better. Since then, my original ocularist retired, but his daughter apprenticed under him and took over the business with her husband, also an ocularist. If in Portland, check out Maloney's Ocularists. And they are very busy. I am due for a new one and can't schedule until August.
Thank you for posting this. Most people I meet have no idea I'm sporting a fake eye! And it is truly a great late night party gag.

So if you are a grown adult, how come they need changing occasionally? What are they made out of and how do they wear out?

A follow up... Do people who are completely blind ever get 2 phony eyes?

Sid, one of the commenters at the main post talked about her uncle, who had two artificial eyes. And the story that accompanies the video http://www.spokesmanreview.com/breaking/story.asp?ID=10174
talks about how Ericson's father pioneered making eyes of plastic.

I knew a girl that only had one eye due to a brother with a BB gun. The only way to remember is when she would pop the fake on in her mouth to wash it off.