An intraocular (IOL) or permanent lens is an artificial lens implanted surgically to replace the eye’s natural crystalline lens that has been damaged by cataract, or to improve vision in patients with severe nearsightedness (myopia) and other vision impairments such as far-sightedness (hyperopia) and astigmatism. The IOL types of lenses that are implanted to improve vision are also called PIOL (phakic intraocular lens), and they are placed in the space between the cornea and the iris, are attached to the iris or placed behind the iris and pupil.