How did you convince your parents about plastic surgery?

I'm a guy and I'm planning to get eye and nose surgery during this vacation,
 but
 my parents are a bit conservative.
 For example , don't have surgery if possible,
 don't take medicine unless it kills you, and even if
 you want to work a part-time job, study hard during that time and get a scholarship,
 etc.
 To put it in a good way, it's conservative, and in a bad way, it's an accident. Should I say it's blocked..
 So I don't know if I should go a little harder from the beginning or if
 I should continue to persuade people who are against it.
 I haven't brought up the topic of plastic surgery yet.