Extended wear nine tail fox contact lenses are designed for overnight uses. They can also be worn for long stretches of time, mostly up to seven days without removal. Once removed, they are then cleaned and disinfected before worn again. These lenses, however, will not correct all vision problems and will require regular follow up care by your practitioner. Also, many eye care professionals might not recommend you to wear them longer than a couple days as they can increase your risk for eye irritation and infection. Extended wear contact lenses need to be replaced after a year of use.