Be sure to read it ^^

I have double eyelids, and I'm thinking of opening the back because I have small eyes, but some people say it's a waste of money because I don't have a lot of tea. Is that really the case? I want the front slit to work well, but I can't because my eyes are a little too focused on it ㅜㅜ People who have slit on the back, please give me some information ^^ And how much does it cost to do the slit on the back?? Is there severe swelling or bruising? I'm going to go to work right away if I don't mind...