Refractive Lens Exchange (RLE) And Intraocular Lens Implants

Refractive lens exchange (RLE) is a procedure that should be reserved specifically for individuals that are significantly presbyopic (reading glasses dependent), who are at least 40 to 50 years of age, and in whom other less invasive procedures (such as LASIK, Epi-LASIK, IntraLASIK, phakic IOLs, and conductive keratoplasty) do not fully meet the individual’s needs.  If you are above the age of 55 or 60, you should strongly consider RLE due to increasing presbyopia.

RLE is a potential option for presbyopic patients who have refractive error including hyperopia (farsightedness) of +1.0 diopter and greater and myopia (nearsightedness) of –1.0 to about –8.0 diopters.  In my opinion, for those individuals who are over the age of 40 and have refractive error greater than or equal to +4.0 diopters of hyperopia, RLE is by far the best refractive surgical option.  If you have more than –8.0 or –9.0 diopters of myopia, RLE may not be your best option due to increased risk of retinal detachment in axially long eyes following RLE or cataract surgery.  However, if you’re about 60 years of age or higher, and cataract surgery is relatively imminent anyway, then RLE may still be your best option even if you’re a high myope, that is, above –8.0 or –9.0 diopters.  If you would like to review your options again, please return to my “refractive surgery Decision Algorithm" page.    

In the refractive surgery armamentarium, RLE is a fairly aggressive procedure with greater potential risks than most other refractive surgical procedures today.  However, there are many, many instances where it is not only a viable option but perhaps the best option.  If you choose RLE, I implore you to find a highly experienced and successful cataract surgeon. 

RLE is essentially the same as cataract surgery, but by its very definition, includes the removal of a clear natural lens as opposed to a cataract.  If a natural lens is cloudy, it is a cataract, and removal of same with a lens implant would be called “cataract surgery with an intraocular lens implant”.  This procedure has more inherent risks than corneal refractive procedures because the lens of the eye is located behind the iris (behind the pupil as well) and thus, removal of the lens and replacement with an artificial implant becomes intraocular surgery.  The only other refractive surgical procedure discussed in this website that requires intraocular surgery is implantation of a phakic intraocular lens (IOL), i.e., the Verisyse™ IOL or the Visian ICL™.  However, the latter procedure poses substantially less risk than RLE because the natural lens of the eye is not removed.

So why would one choose RLE?  First of all, as I’ve mentioned, it is generally only an option for the presbyopic.  All of the other refractive surgical procedures (e.g., LASIK, Epi-LASIK, IntraLASIK, CK, and Phakic IOL’s such as the Verisyse™ IOL and Visian ICL™) cannot directly address the loss of near reading type vision that we experience with aging.  RLE does! 

How is this possible, you ask?  Because when a cataract/refractive surgeon removes the natural lens of the eye, it is possible to implant an IOL that provides both near and distance vision without spectacles.  This is only possible by implanting an  “accommodating IOL” or a multifocal IOL.  Now, to be sure, RLE does not require implantation of either of these types of lenses, but this is the only option that would generally allow distance and near vision simultaneously.  Many patients might choose to have a monofocal IOL implanted, for perceived visual benefit and/or reduced risk.  Bear with me and I’ll try to explain as we cover this chapter.  We’ve got some groundwork to lay here!

Let’s take a look at the refractive lens exchange (RLE) procedure.

The RLE Procedure

RLE is performed using a microincisional procedure. To the patient, this means minimal discomfort during or after surgery, a more speedy recovery of vision, and reduced risk of induced astigmatism. This also generally means less dependence on glasses afterwards. 

Using the illustrations below, I’ve detailed the major steps of RLE using a microincisional procedure, phacoemulsification (ultrasonic lens removal), and a foldable lens implant that is injected into the eye using a lens implant injector. The procedure demonstrates basic principles only.  Eye surgeons use many variations of the general theme, even from one case to another, depending on their own surgical preferences.  

The most commonly used RLE incision is about 3 millimeters in size – just about one-eighth of an inch! Because of the careful construction of this incision and its small size, the incision is generally self-sealing. This translates to a “no-stitch” type operation.      Phacoemulsification Lens Extraction Phacoemulsification is the aspect of the procedure in which ultrasonic vibrations are used to break the natural lens into smaller fragments. These fragments are then aspirated from the eye using the same instrumentation.     Lens Cortex Removal     Once the denser nucleus has been removed, the softer peripheral cortex is removed with the assistance of an irrigation/aspiration handpiece. The backside (posterior) aspect of the capsule is left intact when possible to help support the lens (IOL) implant.    Implanting the Intraocular Lens (IOL)        Lateral View of the Intraocular Lens Implant

In the next step, the surgeon gains access to the natural lens by creating an opening in the  capsule, which is the ultra-thin membrane (about 4 thousandths of a millimeter thick) that surrounds the natural lens.  The surgeon must manipulate instruments inside the anterior chamber, a space that is only about 1/8th of an inch deep.     The surgeon may elect to create grooves in the natural lens, and subsequently break the lens into smaller pieces using the phacoemulsification tip and a second instrument passed through a smaller “side-port” incision.

This lateral view of the IOL implant shows the lens within the “capsular bag,” which is the desired location. This position is the same as that of the natural lens (or cataract, when present) of the eye and, therefore, is generally well tolerated and also provides the most optimal visual results. At this stage, the cataract operation with IOL implantation is complete.

Potential Risks and Complications of RLE

Today, cataract surgery is one of the most successful procedures in all of medicine.  Refractive lens exchange should enjoy the same or perhaps even greater success, given that the procedures are practically identical.   However, complications will still occasionally occur and may range from devastating visual loss to minor inflammation in the eye.  In general, the risk of severe visual loss is very rare, but may occur (as with virtually any procedure) as a result of infection or bleeding inside the eye, or even retinal detachment, the latter of which may occur months or years after a perfectly successful RLE procedure. Most complications are minor, such as swelling of the cornea or retina, increased pressure in the eye, and droopy eyelid. These complications nearly always resolve with medications and continued healing time. 

Selecting An Intraocular Lens (IOL)

When the natural lens of the eye is removed, whether it is clear or a cataract, it is generally replaced with an IOL.  There are a variety of IOLs that are available today, each of which has advantages and disadvantages.  Like refractive surgery itself, we’re beyond the era of “one size fits all”, or in this case, one type (of lens) fits all.   The type of IOL chosen must be tailored to each patient’s individual needs and desires.  Rest assured that the IOLs mentioned in this chapter are all U.S. FDA approved and have undergone rigorous study prior to general use. 

It is important to note, however, that none of the lenses mentioned in this chapter have been FDA approved for RLE.  Each of these IOLs was independently FDA approved and in each and every case implantation of the lens was indicated only for the patient in whom a cataract had been removed.  This does not mean that these lenses should not be used in RLE, however, use of any one of these lenses in RLE is considered “off-label use”.  This is perfectly legal and legitimate but the FDA did not evaluate any of these lenses for any patients other than cataract surgery patients.  This is an important point to understand, not because these IOL’s would behave any differently inside of an eye following RLE than they would if implanted following cataract extraction.  This simply underscores the fact that RLE is a rather aggressive procedure and none of the lens manufacturers have studied, evaluated, or recommended their IOLs for RLE patients.

In this chapter, I’ll review the three fundamental types of IOLs as well as a few specific IOLs that are making an enormous impact on cataract and refractive surgical procedures.  Those three fundamental types of IOLs are conventional (fixed focus) IOLs, accommodative IOLs, and multifocal IOLs.

Conventional (Fixed Focus) IOLs

The conventional monofocal IOL has been used for decades and has shown safety and efficacy with tens of millions of implants in the U.S. alone.  As noted, the conventional monofocal IOL has a fixed focal point, which for most patients, is chosen to provide the best possible distance vision without glasses.  However, because these lenses have a fixed focus, patients will almost always need reading glasses for near vision tasks, assuming the IOL is chosen to provide the best far distance vision possible.  These lenses provide excellent quality of vision under a variety of lighting conditions and have a very low incidence of visual aberrations such as glare, halos, and reduced contrast sensitivity.

There are two monofocal IOLs recently developed and available that appear to be improving the quality of vision beyond any monofocal IOL previously available.  These lenses that provide superior optics have truly advanced  vision into the “high-definition” range, in my opinion.  The two lenses are the Sofport™ AO manufactured by Bausch & Lomb and the Tecnis™ Z9000 manufactured by Pharmacia (a subsidiary of AMO).  Let’s take a deeper look at these two extraordinary lenses.

Sofport™ AO Intraocular Lens

The Sofport™ AO IOL was designed to be aberration free and has an aspheric design that should mimic the quality of vision of a much younger patient.  In fact, this lens might well allow the patient to see like a 20 year old!  Now, I don’t mean to suggest that a patient implanted with this lens would see near and far without glasses, only an accommodating IOL or a multifocal IOL is intended for that.  However, the quality of vision with the Sofport AO may be better than all previous spherical IOLs. 

So what is different about this lens?  The Sofport™ AO was designed with aspheric optics, as opposed to traditional spherical optics of nearly all previous generation IOLs[i].  Spherical IOLs added what is known as positive spherical aberration to the eye’s visual system, whereas an aspheric lens adds no aberration to the optical system of the eye, either negative or positive.

If you look at the eye as a complete visual system, it really has two lenses: the cornea and the natural lens.  The integration of these two refractive surfaces must work hand-in-hand to provide a complete visual system.  The cornea generally imparts positive spherical aberration and has little anatomical change throughout life, at least from an optical standpoint.  The natural lens of the eye has negative spherical aberration at a young age, but as the lens thickens with age, it gradually develops positive spherical aberration as well.  In the eye of a 19 year-old, the positive spherical aberration of the cornea is almost perfectly cancelled out by the negative spherical aberration of the lens, resulting in the sharpest vision and contrast sensitivity that one will ever enjoy.  However, by the age of 60, the positive spherical aberration of the lens adds to the positive spherical aberration of the cornea, and not only is contrast sensitivity decreased but glare and halos at night become common.  Now we understand why the elderly frequently complain about poor night vision, even when they don’t have any eye disease! 

The conventional spherical IOL actually adds to the spherical aberration of the eye because it has positive spherical aberration.  The Sofport™AO lens does not add positive or negative spherical aberration to the eye.  As such, this lens works well in almost all eyes and in a variety of situations, especially in situations of lens decentration, which may occur even in routine uneventful cataract surgery.  In fact, the Sofport™AO lens demonstrated higher optical performance compared with conventional IOLs under all conditions.  It also demonstrated higher optical performance than Pharmacia’s Tecnis Z9000 (to be discussed next) under conditions of decentration, particularly with decentration of 0.5mm or more, which may not infrequently occur following cataract surgery or RLE.

The bottom line with Bausch & Lomb’s Sofport™ AO lens is superior optical performance to any conventional IOL under virtually any conditions and enhanced optical quality over the competing Tecnis Z9000 lens under conditions of decentration in the eye.  I have implanted this lens almost exclusively in my cataract patients over the past five months and I believe the results are not only excellent, but overall better than any other monofocal lens implant. 

Tecnis™ Z9000 Intraocular Lens

The Tecnis™ Z9000 IOL is the first IOL designed with a negative spherical aberration that is an attempt to offset the average positive spherical aberration of the cornea, as reported by optics expert Jack Holladay, M.D. and colleagues[ii].

Using wavefront technology, researchers calculated the wavefront aberrations from the corneas of a cohort of patients averaging 74 years of age.  Using optical ray tracing analyses and a model eye, a prototype (Tecnis™ Z9000) lens was developed that had what is known as a “modified anterior prolate surface”, the latter of which is designed to offset the average positive corneal spherical aberration.  The overall result should provide quality of vision more like that of a typical 19 year-old, assuming the lens is well-centered in the eye and the cornea has approximately an average amount of positive spherical aberration.  As with the Sofport™ AO lens, the Tecnis™ Z9000 lens is a monofocal lens (fixed focus) that will not simultaneously provide near and distance vision.  Once again, only an accommodating IOL or a multifocal IOL is designed to provide near and distance vision without glasses correction. 

In the Holladay et al study, the Tecnis™Z9000 lens showed a reduction in the entire eye spherical aberration that was estimated to occur in 90% of the population.  However, a small percentage of patients have more prolate corneas (steeper in the center) that, when implanted with the Tecnis lens, will have overall negative spherical aberration.  The visual consequences of this are not entirely clear at this time and will require further study.

In two separate studies, the Tecnis lens showed better low-contrast visual acuity and contrast sensitivity (think fog and/or dim lighting, for example, driving on a rainy road at night) than a traditional IOL[iii],[iv]. 

However, when a lens with negative spherical aberration, such as the Tecnis lens, is implanted in the eye and decenters by only 0.4 or 0.5 millimeters, this may induce defocus, astigmatism, and the visual aberration known as coma[v].  Though decentration of this degree is not common, it is estimated that clinically significant decentration occurs in about 3% of cases and “clinically insignificant” decentration occurs in at least 25% of cases[vi].  A certain percentage of cases, however, previously considered clinically insignificant, may become clinically significant if implanted with the Tecnis lens, in my opinion.  This is suggested because of the fact that the lens may induce visual aberrations when decentered.

Overall, I would submit that the Tecnis™ Z9000 IOL is an excellent lens and performs very well in about 90% of patients, assuming the lens is well-centered in the eye (true approximately 90% of the time).  I’ve implanted the lens quite extensively and believe the results, in general, are superior to a traditional spherical IOL.  In a small percentage of cases, patients may experience negative spherical aberration with undesirable visual side effects  and/or reduced vision if the lens is significantly decentered.  This would likely correct, at least partially, with glasses.  It is also important to note that decentration of IOLs is typically not avoidable by anything in the control of the operating surgeon.  This simply has to do with the patient’s anatomy and the capsular “bag”, which contains the lens. 

Accommodating Monofocal IOLs

There is only one lens implant in this category:  the crystalens®, which is a product of eyeonics™.  There is no other lens that truly has accommodative abilities.

So what do we mean by accommodative abilities?  The crystalens® is the first intraocular lens that actually moves inside the eye in response to an attempt to accommodate, that is, to visualize anything at near.  In the past, we could implant our cataract or RLE patients with a monofocal lens implant and, much of the time, reduce their dependence on glasses for distance.  But they had little chance of being able to see at near, assuming they had an implant set for far distance vision.  With the Crystalens®, the ability to accommodate is restored!

Development of the crystalens®

The crystalens® is the brainchild of ophthalmologist, Stuart Cumming, M.D., who spent nearly twenty-five years investigating and developing the crystalens®.  Dr. Cumming worked out of the basement of his own home for years developing various iterations of the prototype lens.  In the early 1990’s, he had developed seven different lens designs that were implanted over a nine-year period under the guidance of Professor Jochen Kammann in Dortmund, Germany.  The first six of the seven designs all accommodated, but all had some dislocations within the eye.  The seventh design, now known as the crystalens®, not only accommodated, but remained in good position within the eye[vii].

On November 14, 2003, the U.S. FDA granted approval for marketing and distribution of the lens for implantation by qualified U.S. surgeons.  As with all of the other lens implants discussed in this chapter, the FDA approved this IOL for use in patients following cataract extraction.  Implantation in the eyes of patients for refractive purposes, that is, refractive lens exchange (RLE), is considered “off-label” use.  If you haven’t read this before in this website, “off-label” use is perfectly acceptable, legal, and legitimate.  This simply indicates that the FDA did not evaluate the product for this purpose.

Function of the crystalens® -- How Does it Work?

The crystalens® is a modified plate haptic lens that has hinges connecting two plates on either side of the lens.  The lens and the plate parts of the lens are made of silicone and the loops on either end are made of plastic.  Once the clear natural lens is removed (in RLE) or a cataract is removed, crystalens® is implanted inside the capsular bag where the natural lens of the eye once rested. 

The crystalens accommodating intraocular lens is engineered with a hinge designed to allow the optic, or part of the lens that you see through, to move back and forth as you constantly change focus on images around you.

Once in place, when the patient attempts to focus at near, the ciliary muscle inside the eye flexes increasing its mass.  This theoretically compresses the vitreous humor in the back of the eye, and the vitreous humor thus pushes the crystalens® forward.  When the lens is pushed forward, the patient sees better up close!  Studies have shown that the crystalens® moves approximately one millimeter forward in response to accommodation, which provides the patient with approximately 1.0 to 1.5 diopters of accommodation, which is enough to allow very good intermediate vision and good near vision. 

Vision Expectations with the crystalens®

FDA studies have shown that patients implanted with the crystalens® generally enjoy near vision without glasses that is substantially better than those implanted with fixed-focus monofocal IOLs[viii].   In the FDA trials for the crystalens®, 98% of patients could see well enough to pass a driver’s license test and read a newspaper without glasses[ix].  Furthermore, vision in the intermediate range, such as viewing a computer screen, is typically excellent with this lens. 

With the eye at rest, the lens moves backward for far distance vision.
Images courtesy of eyeonics™

Taken directly from eyeonics™ website: “The crystalens FDA two-year clinical study results indicate that 92% of the people enrolled in the study (implanted bilaterally) could see 20/25 or better at distance, 96% could see 20/20 at arm’s length and 73% could see 20/25 at near without glasses or contact lenses.”

“What is more exciting is that 98% of these people could pass their drivers test, 100% could see their computer and dashboard, read the prices in the supermarket or put on their makeup, and 98% could read the telephone book or newspaper, all without glasses or contact lenses.”[x]

Multifocal Intraocular Lenses (IOLs)

Multifocal IOL’s rely on a different type of technology to provide near and far distance vision without glasses.  These IOLs utilize concentric rings of power in the lens that are set for various focal points, thus bringing objects at infinite distances into view once the lens is properly implanted in the eye.  These lenses also do not rely on movement of the lens inside the eye in order to achieve their effect, like the crystalens® does.

Multifocal IOLs have achieved excellent results in terms of providing both near and distance vision without glasses, however, these lenses have a slightly greater tendency to cause night vision complaints than monofocal IOLs including the crystalens™.  In fact, loss of contrast sensitivity is absolutely inherent in all multifocal technology.  David Evans, Ph.D., researcher and author in this field of technology, made the following statement regarding this issue: “The multifocal lens is creating multiple focal planes on the back of the eye.  These multiple planes overlap each other and cause aberrations and light scatter, thus reducing contrast sensitivity.”[xi]  Dr. Evans goes on to state that the typical cataract patient may not notice this loss of contrast sensitivity after surgery because he or she had already lost a great deal of contrast sensitivity due to the cataract.  However, for individuals considering RLE, this may not be the case. 

So what does this mean in terms of night vision?  Or vision in general?  Well, multifocal IOLs may be expected to cause a slight reduction in contrast sensitivity, which means that vision might not be quite as sharp as with a monofocal IOL or the crystalens™, or of course, as it probably would be in a normal, healthy, non-surgical eye without a cataract.  Patients implanted with multifocal lenses also have a small chance of glare or halos at night, although with the newer multifocal IOLs, this chance is small.  Nevertheless, as such, I would advise one to be very cautious in choosing a multifocal IOL, especially for the RLE procedure.  I would like to make it very clear, however, that the vast majority of cataract patients implanted with today’s multifocal IOLs are not bothered by night vision complaints.  In fact, as previously stated, they are generally very, very pleased with their visual outcomes.   

The only U.S. FDA approved IOLs in this category are the ReZoom™ and the ReSTOR® lenses.  Let’s look at a bit more detail at the two lens options in this category.

ReZoom™ Multifocal IOL

The ReZoom™ multifocal IOL, a product of AMO (Advanced Medical Optics), is a refractive multifocal lens implant developed for cataract patients that reduces dependence on glasses.  In fact, in the FDA trials conducted prior to approval of the ReZoom™ lens, 92% of those individuals implanted reported that they either “never” or only “occasionally” needed to wear glasses[xii].   To provide a little more detail, 81.4% of patients were independent of spectacles for near vision (approx. 14 to 20 inches), 92.6% were independent of spectacles for intermediate vision (approx. 20 to 34 inches) and 93.4% were independent of spectacles for far distance vision.

The ReZoom IOL

AMO’s ReZoom™ IOL development followed their previous multifocal intraocular lens, the Array lens, which enjoyed substantial success, albeit with a rather high rate of halos and glare.  Neverthelss, the lens did provide patients with distance and near vision without glasses.  Ron Bache, vice president of worldwide marketing for AMO, said that the ReZoom™ IOL “is a next-generation refractive multifocal that improves distance, intermediate and near vision with significantly reduced halos and glare.”

“In dealing with the halos caused by the Array (lens), we knew that they were primarily being caused by the near ad of the lens.  We took the fourth near zone, which was causing most of the halos, and made it 57% smaller.  We also made the third zone, for distance, 70% larger.  The result is that, with the ReZoom, more light is going to distance, reducing halos and glare at night.”[xiii]  Bache has also explained that the ReZoom™ IOL has an “Opti-Edge” design, which further reduces glare.

The ReSTOR®  Multifocal IOL

The ReSTOR®  IOL, a product of Alcon, is a multifocal IOL that uses what is known as apodized diffractive technology to provide patients with a full range of near, intermediate, and distance vision.  However, with this IOL, the best vision is definitely near (14 to 20 inches) and far (beyond three feet) distances, with some significant limitations to intermediate (20 to 34 inch) range vision.  The FDA clinical trials showed that 80% of the individuals in the study did not require glasses at all after receiving the ReSTOR® lens implant[xiv]. 

Like the ReZoom™ lens, the ReSTOR® IOL uses concentric rings of power in the lens to achieve its effect.  However, the ReSTOR® apodization process is one that gradually blends the diffractive step heights of the concentric rings, thus distributing light to near and distant focal points, regardless of the lighting situation.  The type of optics in this lens design is intended to improve image quality while minimizing visual disturbances.                                                    

Regarding visual disturbances in patients implanted with the ReSTOR® lens, rates of severe night vision disturbances, glare, and halos were 4%, 5%, and 5%, respectively.  This is not dramatically different than a comparative (control) group of patients implanted with traditional monofocal IOLs, in which those same visual complaints occurred in 2%, 2%, and 1%, respectively. 

Comparing the ReZoom™ and ReSTOR® IOLs

The ReZoom™ near “add” power, that is, what is equivalent to a reading glass or bifocal, is approximately a +2.25 (at the spectacle plane), whereas the ReSTOR®  IOL effective “add” power is approximately +3.20 at near.  What this means is that the ReZoom™ lens provides good near vision and excellent mid-range (arm’s length) type of vision, whereas the ReSTOR®  IOL provides very good near vision, with somewhat reduced mid-range vision.   Now this doesn’t indicate that the ReZoom™ is better for near vision, in fact, the ReSTOR®  lens should provide the very best “near vision” (14 to 20 inches) of all lenses in this category, however, in providing the best near vision, the lens must sacrifice intermediate range (computer screen) vision.  So, if one is choosing a multifocal IOL, it would be wise to spend some time considering what near visual tasks are most important, that is, do you desire to have your best vision at about 16 inches, where most people hold a book?  If so, the ReSTOR® may be the best lens for you.  If, on the other hand, you prefer to have your best unaided vision at your computer screen’s distance, then the ReZoom™ may be your best choice between these two lenses.  Again, you should ask your EyeMD to help you with this decision! 

I believe both of these lenses have a number of advantages over AMO’s Array multifocal IOL, the United States’ first FDA approved multifocal, which has since been phased out of production.  Overall, I believe the quality of vision is good, but of course, there is the issue that all multifocal lenses will cause some decrease in contrast sensitivity, even if one doesn’t have any symptoms of halo or glare.  If you strongly desire to have near and distance vision without need for glasses, then either one of these lenses may be for you. 

Conclusions

If you’re considering RLE as a refractive procedure, then in my book, I believe you’re probably the best candidate for this if you are a hyperope (farsighted) of +4.0 or greater and you are above 40 years of age, and RLE should be considered by virtually anyone interested in refractive surgery with almost any degree of refractive error who is 55 to 60 years of age or above.

When RLE is completed, the clear natural lens of the eye is replaced with an artificial intraocular lens (IOL), and there are three basic options: 1) Monofocal (fixed focus) IOLs, 2) accommodating monfocal IOLs (crystalens™), and 3) multifocal IOLs.  Each of these lenses has advantages and disadvantages.

Monofocal IOLs have recently been improved and provide excellent vision, although when “set” for far distance, the patient will most definitely require reading glasses for near.  These lenses provide excellent qualitative vision under virtually all circumstances, including various lighting conditions.   

The crystalens™ is an accommodating monofocal IOL that actually achieves far and near vision without glasses; the latter occurs because the lens physically moves forward inside the eye when the patient attempts to view something at near.  This lens provides excellent daytime and nighttime vision, excellent arm’s length (computer screen) vision, and good near vision, though the very near vision may not be quite as good as with the multifocal IOLs.  This lens, because it is a monofocal, provides the patient with excellent contrast sensitivity and little or no risk of nighttime vision complaints, such as halo or glare, which is in contrast to the multifocal IOLs.  Again, in this latter regard, the crystalens™ would behave much like our latest generation monofocal IOLs, except with enhanced near vision.  

The multifocal IOLs may provide the clearest near vision without glasses.  As reviewed, the ReZoom lens probably outperforms the ReSTOR lens for computer length or arm’s length vision, while the ReSTOR outperforms the ReZoom lens for very near vision.  Both of these lenses will cause a slight reduction of contrast sensitivity for the patient, and both lenses will have greater risk of glare and halo at night than a traditional monofocal IOL or the crystalens™. 

I cannot give much further advice on an IOL choice.  As you can see, each of these lens types has advantages and disadvantages.  For those who strongly desire to be glasses independent and have the very best qualitative vision, the crystalens® certainly seems to be the most appealing.  However, if one intends to have the very best “near” vision (14 to 20 inches), then one of the multifocal IOLs might be the best option.  If one doesn’t mind wearing readers at all, then either one of the above mentioned monofocal IOLs would likely be an excellent choice. 

One really has to determine what his or her visual needs are to make the best IOL choice.  Review your options carefully before you choose.  These lenses cannot be easily exchanged, in fact, once a lens implant (excluding the phakic IOLs) has been in the eye for several weeks or more, it usually cannot be safely removed.  So, take your time in making this decision.  It is a decision that you will likely need to live with for the rest of your life.