The Crystalens belongs to a select category of high tech intraocular lenses commonly called 'multifocual intraocular lenses'.
The newest high-definition version of Crystalens to be developed has a design which results in better close vision without sacrificing distance or the quality of intermediate vision.
The disadvantage of these lenses is that as the limited space on multifocal IOLs must be divided into zones, some advantages of seeing through just one zone in single vision lenses are lost, such ascontrast sensitivity.
Contraction and relaxation of the ciliary muscle changes the tension in the zonules, which in turn changes the shape of the lens to provide the correct focusing power for seeing objects at all distances.
On the other hand, while Crystalens can accommodate to allow clear vision at different distances, the lens itself has a single focusing zone.
This makes it less likely to produce side effects such as halos and glare.
Accommodating IOLs can be used in refractive cataract surgery for cataract patients or they can be used in refractive lens exchange (RLE) for people who don't have cataracts, but want lens-based vision correction surgery to reduce the need for reading glasses.
Accommodating IOLs reduce the need for reading glasses by increasing the magnifying power of the eye in response to focusing effort (a process called accommodation).