interocular lens used to replace the crystalline lens when the crystalline lens was removed due to cataract or for some other reason; certainly better than a crystalline lens with a cataract but it does not have the capacity to add extra power which is needed to see clearly up close; progressive addition lenses are a good solution here because they offer a more natural (no line) multi-focal type of vision; UV filters strongly recommended because earlier IOLs did not have UV filters in them, whereas the original crystalline lens protected the retina from UV; new IOLs have been developed that don't have little holes in them, a style superior to the older style that should be asked about when considering this procedure.