Answer:
yes
Explanation:
Well, if they are ok with it. The other person might have something terribly wrong to where they would have to lose their eye. It would be perfectly ethical.
Probably giving them a medication that reacts with their current medication, as it could cause an overdose or other complications
DNA differs from person to person, while organisms and pathogens are prone to each and every single body.
Hope that helped, I am not 100% great at this subject.