Surgically implanted lenses, also called phakic IOLs (intraocular lenses), are an alternative option to high prescription spectacles for people seeking a permanent correction for high prescription of long or short-sightedness. 

The implants resemble contact lenses and are placed between the clear front covering of the eye (the cornea) and either in front of the iris or just behind it.

A key advantage to ICL (Implantable Contact Lenses) implantation, however, is that the lens can usually be removed, and for this reason, the procedure is often termed ‘ reversible’.
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Implantable lenses are a surgical alternative to LASIK for those who do not meet the criteria. For example, people a very high prescription of spectacles, or for those with a very thin cornea may not be suitable for LASIK.

Unlike traditional cataract or lens replacement (PRELEX) the natural lens remains in place and a new lens is placed in front of the natural lens.