Wear contact lenses can help you looking things more clearly. However, you may not sure about how often you need to replace them. While, you have to replace your contact lenses if you have the following conditions:
1. Your contact lenses been damaged or contaminated;
2. Your contact lenses already been used for more than one year;
3. Your vision can not adjust your contact lenses any more;
4. You should use a new pair every day and throw them away each night if you wear disposable contact lenses.
After all, replace your contact lenses at the proper time to keep your eyes healthy.
Although use cycles of contact lenses' are varied from a day, a month, a quarter, a half year and long-wearing, the practical life span mainly depends on the user's condition. If your eyes have no bad reaction, you full can extend it to a longer wearing cycle. But once you find that your eyes are uncomfortable, you'd better change a new pair or wear glasses for a few days. If you get blur vision from your current contact lenses, maybe you wore your contact lenses backwards, if not, you may go change a new pair and check whether your eyesight is changed.