How do i convince my parents to let me wear contacts?

i have been askeing for them for like over a year now but she keeps saying no!i am responsible enuf for them. but she keeps baking up ridculess excuses like "maybe if you keep your room clean for 3 mouths, then i'll think about it!"but seriously, she knows i can barely keep my room clean for that long!! and what does that even have anything to do with contacts??al you have to do is clean them daily, take them out at (depending on what kind you have), and last night i asked and then she made another excuse saying that they are not healthy for my age..~!im 13, my friend siad she saw a doctor give them to an 8 year old!and plus it would be better since i am always breaking my gles or lossing them!i just think she knows i look better without gles and she is trying to keep me ugly ;she doesnt let me wear make up either!no matter what info i give her, no matter how responsible i act she just acts like a donkeys rear end!and she contacts and she nvr evn wears them..cuz shes too lazy~!!~