Premium Intraocular Lenses: The Basics
My practice is largely based on cataract and refractive surgery. Much of the media hype in the last decade has surrounded refractive surgery (specifically Lasik), but cataract surgery remains the most common eye surgery performed in the United States. Most cataracts are age related and usually become visually significant in your 70s or 80s. Occasionally, they can occur much earlier. I’ve performed cataract surgery on people in their 30s and some people are born with congenital cataracts. I’ve also performed cataract surgery on people over 100 yrs old. I tell my patients that cataract development is a natural part of the aging process and that all of us will develop visually significant cataracts eventually if you live long enough.
Cataract surgery involves 2 steps: 1) a technique called phacoemulsification that uses ultrasound energy to remove the dense, cloudy lens/cataract from your eye, and 2) implanting a new lens (also called an intraocular implant or IOL). This article deals specifically with step 2, the IOL, and some of the newer technology that is developing. In recent years, we have seen the emergence of Premium IOLs which are modified lens implants that have capabilities not previously present in standard IOLs. The great benefit of these Premium IOLs is that they have the ability to restore some degree of reading vision to the patient. A standard IOL can be measured and custom fit to an eye to a degree so as to minimize a patient’s postop glasses for distance and this process is considered standard practice. However, a standard IOL has only one focal distance, so the patient is required to have glasses for reading after cataract surgery. Actually, many of us over the age of about 40 to 45 know that the aging eye loses the ability to see up close anyway well before the onset of cataracts. Premium IOLs give us the opportunity to restore some of the youthful accommodating ability of the eye to read up close while getting rid of the cataract at the same time.
The cataract surgery itself is performed in essentially the same manner regardless. The only difference is that a slightly different design of Premium IOL is implanted instead of the standard IOL. Currently, there are 2 basic designs of Premium IOLs. The first is a “multifocal” IOL. The multifocal IOL is a lens which is not just a perfectly optically spherical lens, but instead it has many different optical powers that are blended together by creating several concentric rings on the lens. The two most common lenses are the ReSTOR™ (Alcon) and the ReZoom™ (AMO). Because these lenses have multiple focal points, they can generate decent focused vision at more than one distance. This gives the effect of accommodating to vision at near as well as far away without the use of reading glasses. The second type of Premium IOL is the true “accommodating” design. The accommodating IOL actually changes shape, flexes, or in some way alters its focal power from distance to near. In this way, it very closes mimics what the natural, youthful lens of your eye did prior to age 40. The currently FDA approved IOL of this type is the Crystalens™ (Bausch and Lomb) which has a hinged design that allows it to flex and change its focus for reading. Both of these lens designs have their own particular quirks, but for optical purposes, the accommodating lens is probably the best.
Sometimes, cataract surgery and Premium IOL implantation is combined with refractive surgery or Lasik. This combination is sometimes called bioptics and is done to maximize the visual outcome of the patient at both far and near distances. The calculations for the IOL power are very good but at times they may be slightly off, so Lasik surgery is used as an adjunct to refine the vision correction after cataract surgery. In my opinion, Lasik after cataract surgery is best performed using a bladeless laser system such as the Intralase FS™ system (AMO). This bladeless system is gentler on the eye for 2 major reasons: 1) there is less pressure placed on the eye as compared to the older bladed microkeratomes, and 2) there is no high speed oscillating blade which can be irritating or damaging to the outer surface or epithelium of the eye. Since the post-cataract surgery eye already has an existing incision and is also usually in an elderly patient, I think it is best to avoid the harsher conditions of the bladed Lasik systems. Actually, I use only the bladeless Lasik systems for all of my Lasik patients, whether they’ve had cataract surgery or not.
Ultimately, the Premium IOLs offer a more advanced option to cataract patients, not only to restore lost vision due to cataract, but to turn back the clock to a degree and restore some accommodative vision for near and reading purposes.
