Flew with someone over 20 years ago (FAR 135 commuter) who lost an eye in a car accident. He had to ride with the FAA to check his night vision and depth perception, was given a Class I and later flew as Captain. He had a bad habit of popping his glass eye out during ground-school when he was bored! I also know plenty of cancer survivors, heart bypass, heart attack survivors and those missing a few organs who are still flying. But don't expect to see them flying in Asia.