MULTIFOCAL LENSES

During cataract surgery, your eye’s natural lens is removed and replaced with an IOL. Standard  monofocal IOLs [ those working only for one distance] probably will give you great distance vision, but you usually would require reading glasses for near vision. Newer Presbyopia-correcting IOLs with multifocal designs, on the other hand, provide vision at multiple distances.

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Recent FDA approvals of newer versions of multifocal intraocular lenses (IOLs) for cataract surgery mean even more options are available for people who want to reduce or possibly eliminate their dependence on eyeglasses.

If you are a good candidate for a multifocal IOL and you choose this option, the type your cataract surgeon recommends likely will depend on your unique circumstances, lifestyle and vision correction needs.Currently  these  brands of approved multifocal IOLs are available:

1. Zeiss multifocal lenses

2. AcrySof IQ ReSTOR (Alcon): Two basic multifocal versions of the AcrySof IQ ReSTOR IOL now are available in the United States. The original non-aspheric version, approved in March 2005, provides a diffractive design, which changes the way light is directed depending on where it falls on the IOL’s different zones. This lets your eye achieve focus at multiple distances.

In late 2008, a newer version of the ReSTOR lens was approved. This version has a different near power zone of +3.00 diopters, which enables better vision at intermediate distances. The original version has a +4.00 diopter power that provides better near vision, but with less emphasis on intermediate vision.

3. ReZoom (Abbott Medical Optics or AMO): This intraocular lens is an improved version of the old multifocal Array IOL and uses a design with different zones within concentric rings for focusing at varying distances. Previously the ReZoom was considered the strongest multifocal IOL for enhancing intermediate vision, but now it has competition in that area with the release of the newest ReSTOR IOL.

4.Tecnis (AMO): Like the IQ ReSTOR, the Tecnis uses a diffractive lens design to direct light in different ways — depending on different zones in the lens. Clinical trial results leading to FDA approval in January 2009 demonstrated that having a Tecnis multifocal lens implanted in each eye resulted in 20/25 or better distance vision and 20/32 or better near vision for 93 percent of study participants.

ACCOMODATIVE LENSES [Crystalens]
Another FDA-approved IOL, the Crystalens (Bausch + Lomb), also corrects presbyopia but is not a multifocal intraocular lens. The Crystalens is a monofocal IOL that enables focus at multiple distances by shifting its position in the eye, which provides accommodation.

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Examples of new designs of multifocal intraocular lenses currently in studies include various versions of Acri.Tec IOLs that emphasize various zones for near, intermediate and distance vision.

Also, future versions of existing, approved multifocal IOLs may have toric designs for the additional correction of astigmatism. This likely would reduce the need for astigmatism-correcting limbal relaxing incisions, which are crucial to achieve optimal vision with multifocal IOLs.