I recently suffered severe eye injury and am considering prosthetic. how real do they actually look?

Very: If you receive a well-fitted prosthetic device from a good ocularist they are stunning. When i train medical students in their clinical exam, we always try to include a monocular patient with a prosthesis - never fails to catch a few students.... Lots of fun.

Could look vey real: The prosthetic eye could look real if its done right. Hand made prothetic are finely color painted to matched to the fellow eye. It may be some time fooled for real eye even by other providers.