When you have cataract surgery, the natural lens of your eye is completely removed, and you nearly always receive a permanent, artificial lens at the same time. A plastic disc, called an intraocular (in-truh-OCK-you-lur) lens, or IOL (I-O-L), is placed in the lens capsule inside your eye. This intraocular lens implant has the optical advantage of being placed in the eye like its natural counterpart. The vision correction necessary for your eye is decided by taking into account the curvature of your cornea and the length of your eye, measured by ultrasound, and then implanting a lens of appropriate power. There's no guarantee that the implant will correct your vision perfectly, so the surgeon usually aims to slightly under-correct. The implant restores some of your eye's ability to focus after the old lens has been removed. Virtually all the lenses implanted today are posterior chamber lenses, which are placed in the empty lens bag behind the iris, after the contents have been removed from the eye during surgery. There are numerous styles of IOLs, including foldable IOLs and multifocal IOLs. The style and size of the implant lens chosen for each patient vary, depending on many different factors. Keep in mind that the replacement artificial lens can never have the infinite multi-focusing ability of your natural lens. This means that you'll lose either your near vision or distance vision following cataract surgery, depending on the correction of the artificial lens that's implanted. You'll need to thoroughly discuss with your doctor what your options are as far as the prescription of the lens implant, as well as how the eye that's had the lens implant will interact with your other eye following surgery. Additional corrective lenses may be required to correct your vision to its optimum level. As technology improves, the implants are decreasing in size, and the cataracts are removed using narrower incisions, which decreases healing time.