Accommodating Premium Intraocular Lenses (Crystalens IOLs)
During cataract surgery, tthe natural lens of the eye (which is cloudy, causing poor vision) is replaced with an intraocular lens (IOL) implant. The standard and cheapest option is to implant a monofocal intraocular lens during the procedure, which gives great distance vision. New technology is now producing premium intraocular lenses which use a method called 'accommodation' to give sharper vision at a range of distances.
What is Crystalens?
Currently the only FDA approved accommodating lens is Crystalens, made by Bausch and Lomb. This lens is termed an accommodating lens because it changes its position with the action of the eye muscles to give sharp vision at different distance ranges, much like the eye's natural lens would. When the ciliary muscle of the eye contracts it causes the lens to move forward and the patient can focus on objects that are near. When it relaxes, it allows the lens to reshape and focus on intermediate objects.
Crystalens is known as a 'Premium Intraocular Lens' and is particularly suited to those over the age of 40 who have presbyopia. This condition lengthens eyesight as the focusing system becomes less flexible with age and near sight becomes more difficult. Most people require reading glasses as they reach middle age for this reason. 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 high-definition Crystalens HD also creates less glare or halos with bright lights. In clinical studies, 80% patients who underwent cataract surgery and received a Crystalens implant achieved 20/20 vision or better vision, which is impressive.
Crystalens vs Monofocal Lens
If you receive a standard monofocal IOL during your cataract procedure instead of one that corrects presbyopia, you typically would have great distance vision but would need reading glasses to sharpen near vision. The Crystalens is able to give sharper vision at a wider range of distances; however it is more expensive than a monofocal lens, and is usually not covered by insurance, since the upgrade is considered not medically necessary.
Crystalens vs Multifocal Lens
The most common Multifocal Intraocular Lenses are known by their brand names of ‘AcrySof IQ ReSTOR’ by Alcon and ‘ReZoom’ and ‘Tecnis’ made by Abbott Medical Optics. Multifocal IOLs are designed with different zones over the lens to improve vision at multiple distances. They work in a similar way to progressive lenses in eyeglasses. The brain adapts and chooses the best zone to look through to provide clear vision at all distances.
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 as contrast sensitivity. This determines how well the eye can see in low light and how well it can distinguish objects from similarly colored backgrounds.
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. However the Crystalens may not provide such a range of focus as a multifocal lens and therefore reading glasses may still be required. Also, there are other side effects associated with Crystalens, such as astigmatism, which can happen if the lens shifts position in the eye during the healing process.
Like accommodating lenses, multifocal lenses are considered an optional, “premium” lens, cost more than standard monofocal lenses, and are usually not covered by vision insurance.
There are advantages and disadvantages to both these types of premium intraocular lenses. Before making your final decision, be sure to discuss all your options with your eye surgeon.
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