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Refractive Surgery | Oct 2010

Survey of Accommodating IOL Technologies

A panel of anterior segment surgeons provides answers to five questions.

With the push toward refractive cataract surgery, presbyopia-correcting IOLs are steadily gaining popularity, both with surgeons who are implanting them and with patients who are asking for them. An abundance of multifocal and accommodating IOLs are currently available, and there are more models on the horizon. One area of intense focus is the search for a truly accommodative lens technology. For now, several pseudoaccommodating lenses are either currently available or in the pipeline. The following questions were sent to a panel of anterior segment surgeons who have experience implanting accommodating IOLs.

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
3. What are the advantages of the lens design? The disadvantages?
4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
5. What is your opinion on the future of this lens technology?

This survey is intended to offer a sampling of thoughts on eight accommodating IOL technologies: the Akkommodative 1CU (HumanOptics AG, Erlangen, Germany), the Crystalens AO (Bausch + Lomb, Rochester, New York), the FluidVision (PowerVision, Inc., Belmont, California), the NuLens DynaCurve (NuLens, Ltd., Herzliya Pituach, Israel), the SmartIOL (Medennium, Inc., Irvine, California), the Synchrony (Abbott Medical Optics Inc., Santa Ana, California), the Tek-Clear (Tekia, Inc., Irvine, California), and the Tetraflex (Lenstec, St. Petersburg, Florida). Vision Solutions Technologies (Rockville, Maryland) asked that its LiquiLens not be featured in this survey. Some responses contain forward-looking thoughts and are not necessarily intended to provide clinical information. In some cases, the participant did not respond about a particular lens, and therefore that set of questions was left out.

VICTOR BOHÓRQUEZ, MD

I am currently the Chief of Ophthalmology at Saludcoop EPS – Servioftalmos, in Bogota, Colombia. I have been implanting accommodating IOLs for the past 6 years, and most of my experience has been in clinical research trials with the Synchrony dual-optic IOL (Visiogen Inc.; now Abbott Medical Optics Inc., Santa Ana, California). I have also started implanting the Crystalens HD (Bausch + Lomb, Rochester, New York) this past year. My experience is based on these two accommodating IOLs.

Currently, I implant accommodating lenses in approximately 10% of cataract patients. This percentage is increasing fairly quickly and will rapidly outgrow my percentage of multifocal IOL patients. I prefer implanting accommodating lenses in younger patients because I believe it is a better way to restore natural physiological accommodation and provide good quality of vision at all distances. Multifocal IOLs split incoming light rays into two or more focal points, thus producing uncomfortable photic phenomena.

It is important to mention that there is still no specific IOL that fulfills all needs for all patients. It is ultimately up to the surgeon to carefully select the correct IOL for the patient's individual lifestyle. The challenge for current and future accommodating IOL technologies is to prevent fibrosis and maintain capsular clarity. A functioning capsule is essential for the accommodative mechanism to work properly. As imaging technologies advance, so will IOL design. When accurate capsular bag and ciliary muscle strength measurements are finally possible, custom-designed IOLs will become reality.

CRYSTALENS AO

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I do not have experience with the new version of the Crystalens, the AO, but I have implanted more than 60 eyes with the Crystalens HD.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
I cannot speak for the Crystalens AO. In terms of the HD, it incorporates a small magnitude of negative spherical aberration within the central 1.5-mm diameter region of the 5.0- mm optic. This negative spherical aberration is expected to improve intermediate and near vision by increasing the depth of focus. The mechanism of action of this lens remains unproven.

3. What are the advantages of the lens design? The disadvantages?
[No answer provided.]

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
Most of my HD patients are satisfied, and the lens fulfills most of their needs. These cataract patients accept the possibilities of needing reading glasses for small print and of decreases in contrast sensitivity. The HD lens is a good option for patients who are worried about glare and halos and will accept low-powered glasses for reading. I tend to target minimonovision with 0.25 D in the dominant eye and -0.25 D in the fellow eye, as recommended by Bausch + Lomb.

5. What is your opinion on the future of this lens technology?
[No answer provided.]

FLUIDVISION

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience implanting this IOL.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
My understanding is that this IOL works by moving fluid from the haptics into a bladder in the center of the lens. This movement alters the anterior radius of curvature and shifts the lens forward.

The design could be limited by the development of capsular fibrosis. In case of capsular fibrosis, more fluid would be needed to produce a greater magnitude of accommodation, or, even worse, the lens could get stuck at a single focal point, resulting in large refractive errors.

3. What are the advantages of the lens design? The disadvantages?
[No answer provided.]

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
[No answer provided.]

NULENS DYNACURVE

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
I understand that the flexible polymer, located between two rigid plates, moves posteriorly with accommodative effort to decrease the power of the eye (contrary to human accommodation, which increases the power of the eye to see near objects clearly).

3. What are the advantages of the lens design? The disadvantages?
It may be awkward to ask patients to learn to see near objects by disaccommodation and to do activities like driving or watching a movie by forcing accommodation. Another issue with this lens is that it must be placed in the ciliary sulcus; it is a big lens that may cause iris chafing with resulting inflammation and/or pigmentary dispersion.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
[No answer provided.]

SYNCHRONY

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have implanted the Synchrony in more than 300 eyes.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The rear optic of this one-piece, dual-optic accommodating IOL is a minus lens, with a power chosen to produce the desired overall net IOL power in the patient's eye. The front optic, which is mobile, is always 32.00 D, which inherently provides more accommodation per unit of movement compared with single-optic designs (Figure 1). Also, the Synchrony provides consistent accommodative amplitude regardless of lens power.

Our group has been able to show, utilizing several objective techniques including ultrasound biomicroscopy and iTrace wavefront aberrometry (Tracey Technologies, Corp., Houston), that the lens works according to the Helmholtz theory of accommodation. With accommodation (near stimulus), the ciliary body contracts, releasing zonular and capsular bag tension and allowing forward movement of the anterior optic of the IOL. This results in an increase in the power of the eye (ie, myopization).

3. What are the advantages of the lens design? The disadvantages?
The only disadvantages I have observed are refractive surprises in some patients and restricted movement of the anterior optic in others. Extreme capsular bag sizes can cause refractive errors or lack of anterior lens movement. Currently, we do not have an accurate method of predicting capsular bag volume; however, in the future, if we could measure or estimate the strength of the ciliary muscle and capsular bag volume preoperatively, we could better choose the appropriate technology and lens size that best fits the patient's anatomy.

When compared with other accommodating IOLs and the multifocal IOLs currently available, the Synchrony provides uninterrupted vision at all distances through physiologic accommodation.5-7 The most powerful advantage of this lens is that the subjective and objective evaluations of accommodative amplitude correlate and show approximately 2.00 to 3.00 D, suggesting real and natural accommodation. Additionally, the Synchrony is the only IOL that completely fills the capsular bag, keeping the anterior and posterior capsules apart and thus limiting fibrosis (Figure 2).

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
Our experience with this lens extends to 4 years' followup. Patients have excellent visual acuity at all distances, very functional reading speed (comparable with multifocal IOLs at newspaper print size), and lower incidence of glare and halos than multifocal lenses.

As with other premium IOLs, a careful surgical technique is ideal. The Synchrony is provided in a preloaded injector, and the lens is delivered into the capsular bag in a consistently controlled fashion through a small incision. I attempt a perfect 5.0-mm continuous curvilinear capsulorrhexis (CCC) by creating a guide before my incision with a 5.3-mm corneal marker.

With premium IOLs, I try to decrease the incidence of capsular opacification by cleaning the capsular bag completely, including polishing the undersurface of the anterior capsule to remove lens epithelial cells. I prefer bimanual I/A to achieve 360° polishing, including the subincisional areas.

With any accommodating lens, I want to have a capsule that remains clean and flexible to increase the chances of success. The Synchrony has features that help prevent anterior and posterior capsular opacification. A system of fluid channels on the anterior optic allows aqueous humor circulation between the bag and the anterior chamber and keeps the CCC edge raised, preventing rubbing between the optic and the lens epithelial cells, thus inhibiting lens epithelial cell fibrous metaplasia (a precursor of anterior capsular opacification).

5. What is your opinion on the future of this lens technology?
[No answer provided.]

TETRAFLEX

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The Tetraflex is another single-optic IOL that is much like the Crystalens in its design and anticipated mode of action.

3. What are the advantages of the lens design? The disadvantages?
Based on my experience with other accommodating lenses, I am skeptical of this IOL's ability to generate a significant magnitude of accommodation with vitreous displacement alone.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
[No answer provided.]

Victor Bohórquez, MD, is with the Department of Ophthalmology at Servioftalmos, Bogotá, Colombia. Dr. Bohórquez states that he is a paid consultant to Visiogen (now part of Abbott Medical Optics Inc.). He may be reached at e-mail: vibo4@hotmail.com.

SHERAZ M. DAYA, MD, FACP, FACS, FRCS(ED), FRCOPHTH

I work in both the government sector (National Health Service; NHS) and run a private organization that provides cornea, cataract, and refractive surgery. I have been involved with accommodating lenses since 2002 and commenced with the Crystalens AT-45. I have also used Crystalens' later-generation lenses, the 5-0, the HD, and now the AO. In my practice, I implant accommodating IOLs in 20% of patients.

AKKOMMODATIVE 1CU

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
I believe the lens works by moving forward as a result of vitreous displacement from ciliary body contraction, although this seems to be more dependent on capsule malleability. I gather (anecdotally) that the lens ceases to function once the capsule fibroses.

3. What are the advantages of the lens design? The disadvantages?
Its advantages include four-point fixation and easy implantation through a microincision with the correct injector.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
It will be surpassed by other technologies.

CRYSTALENS AO

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have implanted more than 800 Crystalens IOLs since 2002 and have used the AT-45, the 5-0, the HD, and currently the AO.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
This lens works both by vaulting forward as a result of vitreous movement and by arching; the silicone lens is flexible, and the configuration of the haptics and the hinge seems to permit this process. The limitation is its inconsistency of action. Almost all recipients obtain good distance and intermediate vision, but only 67% get good near vision. Myopes seem to do better, which is a little counterintuitive in that the lens power is low; however, it is easily explained by the fact that eyes with longer axial lengths have a greater depth of focus.

3. What are the advantages of the lens design? The disadvantages?
The AO version has a monocular aberration-free optic, which ensures good visual quality and is forgiving of mild centration and tilt. To reduce the incidence of tilt and refractive change, we now routinely follow a suggestion made by my co-chief medical editor, Erik L. Mertens, MD, FEBOphth, which is to implant a capsular tension ring (Ophtec BV, Groningen, Netherlands) in conjunction with lens implantation.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
Patients who absolutely must drive at night and cannot risk the compromises associated with multifocal lenses and night driving (eg, chauffeurs), those requiring good unaided intermediate vision, and those in whom a multifocal lens is a relative contraindication (eg, patients with glaucoma, age-related macular degeneration, diabetes) are good candidates.

5. What is your opinion on the future of this lens technology?
It is a useful lens to have in our surgical armamentarium. Other technologies that function similarly and do not reduce contrast sensitivity may well replace this lens, unless a new iteration of the implant is developed to provide increased reliability in terms of lens movement.

FLUIDVISION

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
It has an interesting mechanism of action. The sustainability of action might be an issue and may be reduced as a result of capsular fibrosis. Further investigation is required.

3. What are the advantages of the lens design? The disadvantages?
One advantage is the potential for a large amplitude of accommodation. In terms of disadvantages, there is possible decreased performance with time. I would be interested to know about visual performance and aberrations at different levels of accommodation.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
Any patient could be a potential candidate, as long as the device works and does not produce any optical aberrations.

5. What is your opinion on the future of this lens technology?
Unsure, but the future looks good if it works long-term.

Sheraz M. Daya, MD, FACP, FACS, FRCS(Ed), FRCOphth, is Director and Consultant of Centre for Sight and the Corneoplastic Unit and Eyebank, Queen Victoria Hospital, East Grinstead, United Kingdom. Dr. Daya is the Chief Medical Editor of CRST Europe. He states that he is a consultant to Bausch + Lomb. He may be reached at e-mail: sdaya@centreforsight.com.

ROBERT K. MALONEY

I am in a group private practice in Los Angeles. Our center has been implanting accommodating IOLs since 2006. Accommodating IOLs are used in approximately 25% of our cataract surgery patients currently.

AKKOMMODATIVE 1CU

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The accommodative mechanism is similar to the Crystalens; with soft flexible haptics, the optic will move forward in response to vitreous pressure.

3. What are the advantages of the lens design? The disadvantages?
The four-haptic design fills the capsular bag, distending it. This distension may improve the ability of the ciliary body to generate the accommodative force on the lens.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
I have no opinion.

5. What is your opinion on the future of this lens technology?
Because the accommodative mechanism is similar to the Crystalens, I expect the lens to have a future similar to that lens.

CRYSTALENS AO

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I use either the Crystalens AO or the Crystalens HD in approximately 25% of my premium IOL patients.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The lens accommodates when vitreous pressure induces either forward movement of the lens or a distordistortion of the lens, leading to an increase in spherical aberration with increased depth of focus.

3. What are the advantages of the lens design? The disadvantages?
The two-haptic design is easy to insert and requires no significant changes in surgical technique from standard cataract surgery. Because the positioning loops at the ends of the plate haptics become encased in the capsular bag, the haptics cannot be explanted once the bag fibroses, and the haptics must be amputated. However, because of the good optical performance of the lens, explantation is rarely necessary.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
The optimal candidate is a patient who requires excellent distance and intermediate visual acuity, is willing to sacrifice near visual acuity, and would be intolerant to the increased night glare that accompanies multifocal lenses. Because the lens is flexible, the refractive outcome is slightly less accurate than with a standard monofocal lens, so the surgeon must be prepared and able to perform a laser corneal surgical refractive enhancement postoperatively.

5. What is your opinion on the future of this lens technology?
The lens has a secure position in our armamentarium now because it offers an alternative for patients who want a premium IOL but who are intolerant of the night glare of multifocals.

FLUIDVISION

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
Because the lens relies on the movement of fluid behind the membrane, it potentially has a much greater amplitude of accommodative power than a solid lens.

3. What are the advantages of the lens design? The disadvantages?
[No answer provided.]

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
[No answer provided.]

SYNCHRONY

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The Synchrony entirely fills the capsular bag (Figure 3), maximizing ciliary action. The combination of its plus and minus optics increases its accommodative response to ciliary movement.

3. What are the advantages of the lens design? The disadvantages?
[No answer provided.]

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
I am looking forward to adding this lens to my practice when it is available in the United States.

TETRAFLEX

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The accommodation of this lens may occur when ciliary pressure causes the lens to flex, inducing a change in spherical aberration and increasing the depth of focus. The lens has a four-haptic design and is vaulted anteriorly, which may improve the response of the lens to ciliary movement.

3. What are the advantages of the lens design? The disadvantages?
[No answer provided.]

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
[No answer provided.]

A FINAL COMMENT

We are moving into a generation of accommodating lenses with accommodative amplitudes dramatically increased over what has been previously available. An unrecognized problem with these lenses is that they will have less refractive accuracy than the lenses we are used to. The reason for this is simple: these lenses are designed to respond to small changes in the ciliary force with large changes in refractive power.

Because of variations in the sizing of human eyes and variations in capsular bag contraction, the resting force on the lens with the ciliary muscle relaxed will vary significantly from patient to patient. Therefore, many of these lenses will be in a partially accommodated state even with the ciliary muscle relaxed. We should expect to see larger spherical refractive errors in these lenses than we are accustomed to. To use these lenses, the cataract surgeon will need to be an expert refractive surgeon as well.

Robert K. Maloney, MD, is the Director of the Maloney Vision Institute in Los Angeles. He states that he is a consultant to Abbott Medical Optics Inc. and is a consultant to and an owner or shareholder in Calhoun Vision, Inc. Dr. Maloney may be reached at tel: +1 310 208 3937; e-mail: info@maloneyvision.com.

SAMUEL MASKET, MD

My practice concerns mainly complex anterior segment cases. As a result, I see a relatively small number of routine cataract candidates, limiting the number of patients who are eligible for either multifocal or accommodating IOLs. With that said, I have implanted accommodating IOLs for nearly 3 years and they represent between 5% and 10% of my cases. All surgery is performed at Specialty Surgery Center, an outpatient center dedicated to anterior segment eye surgery

AKKOMMODATIVE 1CU

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no clinical experience with the Akkommodative1CU, as it is not available in the United States.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
Given low market interest where available and because it has been on the market for several years, I doubt that it achieves much accommodation.

3. What are the advantages of the lens design? The disadvantages?
Today, focus-shift, single-optic IOLs are of limited value.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
In my opinion, the future of this technology is limited.

CRYSTALENS AO

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have implanted approximately 100 of these lenses.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
Its mechanism of accommodation is speculative; in concept, it is a single-optic, focus-shift lens with little true movement demonstrated. Some patients have an improved accommodative range over monofocal lens designs, but this is not predictable. The Crystalens HD model improved near visual acuity but at the expense of vision quality and IOL power predictability.

3. What are the advantages of the lens design? The disadvantages?
The disadvantages include the size of the optic (5 mm), lack of a UV-absorbing chromophore, and its flexible haptics, which, in combination with postoperative capsular fibrosis, leads to mild to severe Z syndrome.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
This lens serves those who desire reduced spectacle dependence and are willing to accept limited near UCVA. Patients are best served with mini-monovision. During implantation, it is imperative to clean anterior subcapsular lens epithelial cells and to cover the haptics with the anterior capsule to prevent Z syndrome. I prefer an ovoid capsulorrhexis, placing the long axis of the optic perpendicular to the short axis of the capsulotomy. I offer this IOL to those who are not appropriate candidates for multifocal IOLs.

5. What is your opinion on the future of this lens technology?
It will be replaced by evolving IOLs.

FLUIDVISION

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
No personal experience; however, I am a member of the medical advisory board.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
Accommodation is accomplished by transfer of fluid from the haptic reservoirs to a bladder within the optic on accommodative demand (Figure 4). It has been demonstrated to work in the laboratory and in a small number of humans.

3. What are the advantages of the lens design? The disadvantages?
The advantages include adequate range of accommodation. Disadvantages include its novel technology, sizing issues of the capsular bag, and the necessary incision size of approximately 5 mm.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
This lens will soon enter clinical trials.

NULENS DYNACURVE

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have implanted this IOL only in the wet lab setting.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
Reverse accommodation is achieved by impaling the haptics in the ciliary body, avoiding the need for capsular bag shape change.

3. What are the advantages of the lens design? The disadvantages?
The main advantage is the potential for sulcus placement, which may also be disadvantageous. The major disadvantage is its mechanism of reverse accommodation.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
Speculative.

SMARTIOL

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have done prior laboratory testing in a few cadaver eyes (Figure 5).

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
Its full-sized optic allows transmission of capsular forces to induce IOL shape change.

3. What are the advantages of the lens design? The disadvantages?
Advantages include its full-size hydrophobic acrylic thermoplastic optic. The disadvantages include IOL sizing and flexibility of material.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
No information at this time.

5. What is your opinion on the future of this lens technology?
Speculative but hopeful.

SYNCHRONY

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
None implanted.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
This lens' double-optic Galilean telescopic design provides the mechanism of accommodation, allowing true accommodation.

3. What are the advantages of the lens design? The disadvantages?
Advantages include its double optic, which fills the capsular bag. The major disadvantages are the large incision size required and the need for perfect surgery.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
This lens will likely have favorable market position for several years.

TETRAFLEX

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The lens has a single optic and the haptics are flexible. However, it is a focus-shift IOL.

3. What are the advantages of the lens design? The disadvantages?
Advantages include simple insertion and acrylic material. A disadvantage is limited accommodation due to the single-optic, focus-shift design.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
Should it receive US Food and Drug Administration (FDA) approval, it will have some impact on the market, although its accommodative function is limited.

Samuel Masket, MD, is a Clinical Professor at the David Geffen School of Medicine, UCLA, and is in private practice in Los Angeles. Dr. Masket states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +1 310 229 1220; e-mail: avcmasket@aol.com.

MARK PACKER, MD, FACS

I practice in the beautiful valley town of Eugene, Oregon, nestled between coastal hills and the towering Cascade Mountain volcanic peaks, home to the University of Oregon, the birthplace of Nike footwear, and the last refuge of the 1960s generation. Our private practice and surgery center enjoy a reputation for superb, state-of-the-art cataract and refractive surgery, built and maintained for more than 40 years by offering the most advanced and effective technologies and delivering them with genuine care for each person who trusts his or her sight to us.

This year to date, 35% of my patients have opted for presbyopia correction at the time of cataract surgery. Of these patients, 20% have received an accommodating lens (the Crystalens AO is the only accommodating IOL currently available in the United States; however, I am an investigator for the Synchrony and have implanted it under an Investigational Device Exemption [IDE] in some cases). The other 80% of patients have received multifocal IOLs, predominately the Tecnis Multifocal (Abbott Medical Optics Inc.). In general, currently available multifocal IOLs provide a higher level of spectacle independence than the Crystalens—albeit at the cost of some reduction in quality of vision. However, for patients motivated to live without glasses, multifocal lenses achieve a high level of satisfaction. Future accommodating lenses should achieve a higher level of spectacle independence by providing a greater amplitude of accommodation or pseudoaccommodation and preserve high-quality vision with low overall optical aberrations.

AKKOMMODATIVE 1CU

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no personal experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
I remember its launch with great fanfare at the European Society of Ophthalmology (SOE) in Istanbul, Turkey, in 2001; however, to the best of my knowledge, it has not demonstrated more than 1.00 D of accommodation.

3. What are the advantages of the lens design? The disadvantages?
There have been reports of capsular contraction and centripetal movement of the haptics.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
Unless improvements in its design are forthcoming, I do not believe the 1CU will remain a viable entry.

CRYSTALENS AO

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have extensive experience with the Crystalens, beginning as an investigator in 2000 with the AT-45 and spanning the decade since.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
Axial movement was the initial conceptual mechanism of this lens, but it has not been demonstrated to move significantly. Alternative explanations for its clinical effectiveness include arching, bending, and high spherical aberration. The FDA approval for the Crystalens described 1.00 D of accommodation, and I believe this accurately represents a mean minimum. Some patients achieve higher levels of function, perhaps from pseudoaccommodative mechanisms.

3. What are the advantages of the lens design? The disadvantages?
I had minimal trouble with complaints of halo after Crystalens HD implantation, but I have heard of this phenomenon from other surgeons. The current AO design provides optical quality similar to a monofocal IOL.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
I continue to recognize that some patients do extraordinarily well with this technology, and that these patients tend to be axial myopes with minimal astigmatism and little to no residual refractive error. It is not unusual to achieve 20/20 and J2 or better vision in this group. On the other hand, the majority of patients implanted bilaterally with any model of the Crystalens should be counseled to expect to wear low-power reading glasses postoperatively (usually 1.25 to 1.50 D). I continue to offer the Crystalens AO, primarily for patients who specifically request it and secondarily for patients who wish to reduce their need for glasses but are averse to halos or dysphotopsia. I discourage hyperopes and patients with higher degrees of keratometric cylinder preoperatively unless they are comfortable with the high likelihood (about 15%) of an excimer laser enhancement procedure afterward.

5. What is your opinion on the future of this lens technology?
The Crystalens is currently experiencing a declining market share in the United States; however, it has been reimagined and redesigned several times and may have yet another rebirth in store.

FLUIDVISION

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have seen the design of the FluidVision lens and heard some reports about it at meetings. I have no personal experience.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
I believe the concept could be effective; however, I am concerned about long-term safety.

3. What are the advantages of the lens design? The disadvantages?
It may provide substantial accommodation.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
This design has some potential; however, there is a long clinical row yet to hoe.

NULENS DYNACURVE

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no personal experience.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The NuLens represents a captivating and innovative idea; however, its embodiment is complex and fraught.

3. What are the advantages of the lens design? The disadvantages?
This design has the ability to provide high amounts of accommodative amplitude through changes in the surface curvature of the deformable piston. The device is fairly complex and much different from anything we have experienced before.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
This technology has developed a great deal since I first became aware of it. With greater simplification, it may yet prove itself.

SMARTIOL

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no personal experience.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The SmartIOL has been off my radar screen for some time. Several years ago it was a hot topic, with benchtop videos of its expansion in warm water and its inherent flexibility.

3. What are the advantages of the lens design? The disadvantages?
Simple, straightforward and easy to implant, it seemed at the time to be a winner design. Even the potential complication of posterior capsular opacification seemed manageable because Nd:YAG capsulotomy would not be contraindicated. At the moment, I am wondering what became of the SmartIOL.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
[No answer provided.]

SYNCHRONY

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
As a US investigator for this lens, I have been able to implant it under an IDE in some cases.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The Synchrony represents a unique combination of original design, ingenuity, and functionality. I have been extremely impressed by the demonstration of forward movement of the anterior optic with ultrasound biomicroscopy under ciliary body contraction.

3. What are the advantages of the lens design? The disadvantages?
The resultant 2.00 to 3.00 D of accommodation provides intermediate vision that outperforms multifocal IOLs and near vision that matches them, without the induction of aberrations. The persistent clarity of the capsule beyond 3-year follow-up is an unexpected benefit of this IOL.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
The surgical technique demands a precise capsulorrhexis and careful cortical clean-up; the injector provides a simple and predictable method of implantation.

5. What is your opinion on the future of this lens technology?
Acquired by Abbott Medical Optics Inc. last year, the Synchrony is awaiting FDA approval. I believe it has the potential to become a dominant market player in the near-term.

TEK-CLEAR

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no personal experience.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The Tek-Clear is a lens within a ring; it is a bending, accommodating IOL. It is not available in the United States.

3. What are the advantages of the lens design? The disadvantages?
It is a simple design, but one that does not appear to have the potential for greater accommodative amplitude than the Tetraflex or the Crystalens.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
I do not see this IOL garnering a significant market share.

TETRAFLEX

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no personal experience.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The Tetraflex reportedly works through a bending-and- flexing mechanism, with changes in surface curvature and possibly some axial movement.

3. What are the advantages of the lens design? The disadvantages?
The Tetraflex appears to provide a range of function similar to the Crystalens.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
The Tetraflex may have some adherents, but is unlikely to be a big winner in the market place.

Mark Packer, MD, FACS, is a Clinical Associate Professor at the Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, and is in private practice at Drs. Fine, Hoffman & Packer, LLC, Eugene, Oregon. He states that he is a paid consultant to Abbott Medical Optics Inc., Advanced Vision Science, Bausch + Lomb, Carl Zeiss Meditec Surgical, Inc., Celgene Corp., Corinthian Ophthalmic Inc., GE Healthcare, Haag-Streit USA, Ista Pharmaceuticals, Inc., and Rayner Intraocular Lenses, Inc., and holds stock options with LensAR, Inc., Surgiview LLC, Corinthian Ophthalmic, Inc., Transcend Medical, Inc., TrueVision Systems, Inc., and WaveTec Vision Systems. Dr. Packer may be reached at tel: +1 541 687 2110; e-mail: mpacker@finemd.com.

MAGDA RAU, MD

In Germany, I practice in the hospital setting at Augenklinik Cham and also am in private practice at Refractive Privatklinik-Dr.Rau, both in Cham. I also practice at Eye Centre Prag in the Czech Republic. I have been implanting accommodating IOLs for the past 9 years. Currently, I use accommodative technologies in 15% of my cataract patients.

AKKOMMODATIVE 1CU

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have used the 1CU regularly since 2001; I have implanted approximately 500.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The accommodative function is based on the focus-shift principle; the flexible geometry and composition of the four haptics allow the IOL to move forward in correspondence with the ocular structures such as the ciliary muscle. Successful performance of the lens depends on the healthy physiology of the accommodating structures of the eye.

A forward lens movement of 0.64 to 1.10 mm achieves 0.50 to 1.80 D of accommodation. Higher lens powers (starting at 23.00 D) increase the amount of pseudoaccommodation. Additionally, according to the principle of the conoid of Sturm (astigmatmus inversus against-the-rule), astigmatism of -0.50 to -1.25 D increases the amount of pseudoaccommodation achieved after the implantation of 1CU.

3. What are the advantages of the lens design? The disadvantages?
Pseudoaccommodation is achieved through deformation of the haptics, so the monofocal nature of the lens optic avoids the typical side effects (eg, glare and halos) associated with multifocal IOLs. Patients do not have to get used to two different foci, which for some is difficult. In my opinion, the greatest advantage of this lens is that it can be offered to patients who wish to be spectacle independent but do not want to compromise distance vision; who drive a lot at night; or who work in an illuminated environment, such as under spotlights on the stage.

The disadvantage is that the achieved accommodation is usually only 1.00 to 2.00 D, contraindicating patients who want 100% spectacle independence.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
The ideal candidate wants spectacle independence in daily life; these are active people who work on the computer, play sports and cards, go to the cinema, and drive at night. Candidates who read often, work a lot at near, and desire complete spectacle independence are not ideal candidates for this IOL. I usually start with the dominant eye and calculate the refraction target for plano. After 1 month, if the patient requires better near vision, I calculate the lens for the nondominant eye for between -0.50 and -1.25 D. I implant the 1CU through an astigmatically neutral clear corneal incision. It is important to perform a well-centered rhexis, without any peripheral tears and not exceeding 5 mm in diameter, to ensure that the capsule is stable enough to withstand any IOL movement. As it might hinder the shift of the IOL, no capsular tension ring should be used. Patients with symptoms that might hinder the accommodative mechanism, such as pseudoexfoliation syndrome, synechia, phacodonesis, or damaged zonules, should be fit with another IOL.

5. What is your opinion on the future of this lens technology?
In my practice, I use the 1CU as a complement to multifocal IOLs. This lens addresses the needs of patients who wish to achieve spectacle independence. In the future, it may be possible to combine the flexible haptics with movement-induced changes of the lens optic material. This could increase pseudoaccommodation to 3.00 D. I think that there will continue to be further need for accommodating IOLs, because although multifocal IOLs continue to emerge in the market, not every patient is a good candidate for this lens design.

CRYSTALENS AO

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have implanted approximately 10.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
[No answer provided.]

3. What are the advantages of the lens design? The disadvantages?
In my opinion, results after implantation of the Crystalens AO are comparable with results after implantation of the Akkommodative 1CU. Therefore, the advantages and disadvantages of both IOLs are nearly the same.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
For patients to achieve more spectacle independence, I correct the nondominant eye to -0.50 or -1.00 D. Women seem to tolerate slight monovision better than men. In my experience, 25% of women and 15% of men have been able to adapt to monovision. For this reason, I usually target higher monovision in women than in men. We examine the tolerance of monovision preoperatively with test glasses or contact lenses. Even after 10 minutes with test glasses, patients can usually tell if they will tolerate monovision.

5. What is your opinion on the future of this lens technology?
[No answer provided.]

TEK-CLEAR

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have implanted three lenses thus far.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The Tek-Clear is a successful attempt to simulate the human lens. Designed to take advantage of the natural accommodating process of the human eye, the lens haptics and optic incorporate a bending-beam approach that fully optimizes IOL movement as the ciliary muscle contracts and relaxes during accommodation.

3. What are the advantages of the lens design? The disadvantages?
Unfortunately, even though the lens is very flexible, with its large diameter it is difficult to implant. The accommodation achieved in our hands with this lens was 1.00 D.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
[No answer provided.]

Magda Rau, MD, is the Head of the Augenklinik Cham and Refractive Privatklinik-Dr.Rau, Cham, Germany, and Eye Centre Prag, Czech Republic. Dr. Rau states that she has no financial interest in the products or companies mentioned. She may be reached at tel: +49 9971 861076; e-mail: info@augenklinik-cham.de.

SUNIL SHAH, FRCOPHTH, FRCS (ED), FBCLA

I work both in the Midland Eye Institute, a dedicated private ophthalmic day hospital, and the Birmingham and Midland Eye centre, an NHS hospital, both in the United Kingdom. I have been using accommodating lenses for more than 6 years, both for research trials and in routine practice. I use accommodating IOLs for appropriate patients and feel that they are a necessary part of my armamentarium to offer patients a complete range of choices.

AKKOMMODATIVE 1CU

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have implanted 50 lenses. Initially, this was part of a study.8

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working? Theoretically, it is the focus-shift principle that provides provides the mechanism of accommodation. In practice, it is probably lens flexing.

3. What are the advantages of the lens design? The disadvantages?
I found the lens to be slightly fiddly to insert. Additionally, in my experience, it provided only limited pseudoaccommodation and had a high early posterior capsular opacification rate.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
I do not use this lens any longer.

5. What is your opinion on the future of this lens technology?
Limited.

CRYSTALENS AO

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have no experience with this lens.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
Like the Akkommodative 1CU, the mechanism is theoretically the focus-shift principle. However, in practice, it is probably the lens flexing.

3. What are the advantages of the lens design? The disadvantages?
There are few advantages other than the marketing by the manufacturer.

4. Who is the ideal candidate for this lens? Do you have any tips for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
Limited, given other lenses on the market now.

SYNCHRONY

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
My only knowledge of this lens comes from presentations made at conferences.

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
The focus-shift principle works better in a lens with a dual-optic design, such as this one.

3. What are the advantages of the lens design? The disadvantages?
The advantage is that more pseudoaccommodation is possible. However, it is a large lens and more difficult to manage. Additionally, it may induce myopia for a few weeks after surgery.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
[No answer provided.]

5. What is your opinion on the future of this lens technology?
This is an interesting technology. I look forward to seeing whether it lives up to its potential.

TETRAFLEX

1. Do you have any experience with this lens, either in practice or in clinical testing? If so, how many have you implanted?
I have implanted approximately 1,000. Initially this was through a research study.9 I have recently completed another research study on this lens.10

2. Whether or not you have personal experience with this lens, what is your impression of its mechanism of accommodation? Why does it work, or what in its current design limits it from working?
Theoretically, like the Akkommodative 1CU and the Crystalens AO, the focus-shift principle is the mechanism of accommodation, but in practice it is probably the lens flexing.

3. What are the advantages of the lens design? The disadvantages?
The main advantage is that this lens is simple to use, as it behaves just like a monofocal lens for insertion. It performs very well on functional visual acuity testing even though push-pull testing gives only a mean of approximately 1.60 D pseudoaccommodation. However, the posterior capsular opacification rate is slightly high.

4. Who is the ideal candidate for this lens? What tips do you have for implanting this lens or optimizing postoperative visual acuity?
Anyone who desires good distance and intermediate vision and some near vision, without the risk of dysphotopsias. This lens is ideal for micro-monovision or for patients who are slightly myopic in both eyes.

5. What is your opinion on the future of this lens technology?
This lens has good potential, and I understand it is due to receive FDA approval soon.

Sunil Shah, FRCOphth, FRCS(Ed), FBCLA, is a Visiting Professor at the School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland; Visiting Professor at the School of Life & Health Sciences, Aston University, Birmingham, UK; Medical Director, Midland Eye Institute, Solihull, UK; and Consultant Ophthalmic Surgeon, Birmingham & Midland Eye Centre, Birmingham, UK. Professor Shah states that he is a consultant to Abbott Medical Optics Inc. and Lenstec Inc. He may be reached at tel: +44 1217112020; fax: +44 1217114040; email: sunilshah@doctors.net.uk.

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