Well, frankly speaking, I buy colored contact lenses with my own money. To persuade adult is not a easy thing. First you should list the advantages of wearing colored contact lenses. Wearing colored contact lenses is not only for beauty but economy. Since colored contact lenses is also contact lenses, it has the function of contact lenses. What's more, it makes my eyes different. Second, you should also list its disadvantages, however those disadvantages are not unique. So de contact lenses. Third, you should promise you will protect your eyes carefully. Fourth, if your parents still disagree, you can try my method. Use your own money.
Your parents must have been afraid of disadvantages of wearing the colored contact lenses. They may think the wearing may be bad for your eyes. You need to promise them of your right way of wearing colored contact lenses. You should say that you will not wear them for more than eight hours a day. You should at the same time tell them the advantages of wearing the colored contact lenses which will make your eyes look big and beautiful.
First of all, if you are still under eighteen years old, then it is better not to wear any kind of eye contact lenses including colored contact lenses. This is because that people under eighteen are still in the exuberant period of body growth and development during which their eyeball optical axis have not been well set yet, and thus their eyeballs can easily be malformed if wearing the contact lenses. In addition, people under eighteen get relatively poor self health care consciousness and self-care ability, and wearing contact lenses can easily lead to eye problems. Therefore, it is inappropriate for the children and teenages to wear any kind of eye contacts. Besides, colored contact lenses contain much pigments on the surface of the lenses, which can do harm to the eyes if people wear them for too long a time. Even if you are an adult, you had better not wear colored contact lenses too much, just wear them five days at most, less than eight hours each day.