Multifocal Intraocular Lenses for Cataract Surgery

Intraocular lenses (IOL) are prosthetic lenses that are used to replace natural lenses in intraocular lens surgery, such as surgery to remove cataracts. During cataract surgery, the natural lens is removed and a clear lens is inserted in its place. In the past, cataract patients were offered a monofocal implantable lens designed to improve either distance vision or near vision, but not both. Most patients chose to have their implants focused for distance. Reading glasses or bifocals were then required for intermediate and near focusing. Today, multifocal intraocular lenses are beginning to replace monofocal intraocular lenses because they allow correction at all distances, making vision as natural as possible. These lenses are called presbyopia-correcting IOLs.

Presbyopia-correcting IOLs are not considered medically necessary, so they are not usually covered by Medicare or other health insurance companies. Traditional monofocal implants, however, are usually covered by insurance and Medicare. As a result, most surgeons charge a fee or an upcharge to traditional cataract surgery. This fee ranges from about $1,200 to $3,500. Technology in presbyopia-correcting IOLs is changing rapidly. The various types currently available are usually divided into three broad categories: multifocal IOLs, extended depth of focus IOLs, and accommodative IOLs. 

Accommodating IOLs

These IOLs are designed to work with the ciliary body, a small muscle inside the eye. The ciliary body is a part of our normal near point focusing mechanism that we use throughout our lives. This muscle contracts each time we attempt to focus on something at a close range. When it contracts, it allows our natural lens to change shape, increasing power in order to bring near items into focus.

When accommodating IOLs are inserted into the eye, the ciliary muscle contracts and allows the IOL to physically move and change position. These IOLs have small hinges that allow for this movement to create clear near, intermediate and distance vision. Accommodating IOLs more closely simulate normal vision and have the least amount of unwanted visual sensations, such as glare or halos. However, they may not deliver enough near focusing power for some patients.

Examples 

Crystalens IOL: Originally FDA-approved in 2004, Crystalens improved its original version and gained FDA-approval in 2008. FDA studies show that 80% of patients who used the Crystalens HD could see 20/20 at near after four months. Crystalens tends to give a little better vision at distance and intermediate zones and is an excellent choice for people who perform close work or hobbies.

Other accommodating IOLs:

• Synchrony
• FlexOptic
• Smart
• FluidVision
• TetraFlex

Multifocal IOLs

These lenses are designed to allow for distance, intermediate and near focusing and do not depend on the ciliary body muscle. Most of these lenses have some type of concentric rings etched into the surface that allows images at all distances to be focused on the retina. Because of this, it takes a little longer for people to adapt to them. The focusing power provided by these lenses is different than normal focusing that most people had during their younger adult life. Therefore, the brain must adapt to this new way of focusing. However, they work surprisingly well.

Examples

• ReZoom: uses five different optical zones microscopically etched into the surface of the lens to provide near, intermediate and distance vision
• Tecnis Multifocal: considered a "diffractive" IOL, containing diffractive rings that extend the entire length of the diameter of the lens; improves night vision and reduces dependence on the size of the pupil.
• ReSTOR: uses technology that is dependent on pupil size to provide clear vision at all distances, with an aspheric option to improve night driving and reduce unwanted glare and halos
• Panoptix: This is the only FDA approved trifocal lens available. It is designed to give intermediate and near vision along with distance.
• Tecnis Symfony: This uses an "echelette" design, which elongates the focal point to allow for depth of focus. 

To find out which lens is best for you, it's best to talk to your healthcare provider. Most eye surgeons will complete a lengthy interview about your lifestyle, occupation and how you use your eyes on a day-to-day basis to help you select the lens to fit you best.