IOL is an intraocular lens. It is a surgical replacement for the lens of the eye. It is used mostly in cataract surgery, and is made from silicone or acrylic polymers. The design of the IOL has changed over the last few years and they fit better, leading to fewer complications than before. Non-foldable IOLs are used in conventional cataract surgery. A foldable lens should be used if you want many of the advantages of phacosurgery.