Contact lenses have at least two other purposes aside from correcting vision in the same manner as glasses. These are to change temporarily the curvature of the cornea and for decorative purposes. The procedure that seeks to change the eye curvature is called orthokeratology. They are commonly prescribed to be worn while sleeping and are removed upon awakening. Vision correction, however, may wear off during the day as the effect is only temporary.
Non-corrective lenses, also called plano are used for decorative purposes only such as changing the color of the eye or for some effects as in Halloween themes.