IOL innovations: are we there yet?

Without a doubt, one of the hottest topics in cataract surgery has been the new premium IOLs, specifically the multifocal, toric and accommodating lenses. New designs have yielded improved visual outcomes, less complications, happier patients and, of course, more contented surgeons. But when we consider how much progress has been made in lens research and development, one question remains: are we completely happy with what we have now?

Although the new generation of multifocal IOLs have changed the face of cataract surgery dramatically - surgeons can now treat presbyopia and decrease spectacle dependence - they do not present the perfect solution for all patients. For example, glare and halos are likely with some models and the inability of the lenses to correct vision at all distances has forced some surgeons to mix and match different types of lenses in certain patients.

Some also feel that the accommodating IOLs that are currently available have simply provided a small glimpse of the potential that this exciting lens class can offer.

Nonetheless, everybody is talking about IOLs. Despite the fact that R&D has yet to yield the perfect solution for all patients, one cannot deny that we've come a long way.

"Toric IOLs marked one of the most significant developments in 2007," said Jorge L. Alió, MD, PhD. Although lenses, such as Acri.Tec's bitoric lenses, STAAR's toric ICL and Ophtec's Artisan toric lens have been available for some time, their use has certainly become more widespread more recently. Pavel Kuchynka, MD, was in agreement; specifically he felt that Alcon's AcrySof toric IOL signified one of the biggest market developments in cataract and refractive surgery in 2007.

These astigmatism-correcting IOLs have been praised for their ability to provide cataract patients with good refractive correction for the astigmatic cornea in a single procedure.

Furthermore, H. Burkhard Dick, MD, has been impressed by the toric foldable iris fixated phakic IOL, i.e. the Artiflex/Veriflex (Ophtec/AMO), particularly because this lens is implantable through a small incision, thus inducing less astigmatism. "Not only can we treat ametropia with this lens, but we can also treat astigmatism and we can do this in one step without the need for an additional procedure, such as a limbal relaxing incision. This is great," enthused Professor Dick.

The rise of the multifocals

The multifocal lenses have also been hailed as one of the most outstanding developments in the field of cataract and refractive surgery. In the past, surgeons only had one multifocal lens at their disposal. Now, they have a choice; not only can they provide a solution that matches the professional needs of the patient but they can also take their hobbies and interests into account.

"The arrival of the new generation of multifocal IOLs has meant that we can guarantee our patients good near and far vision, whilst preserving vision quality. In fact, these lenses seem to have resolved the problem of loss of contrast sensitivity in scotopic conditions and the other symptoms of dysphotopsia that were apparent with the first generation of lenses," said Alessandro Franchini, MD.

The multifocal lenses have undeniably changed the practice of cataract surgery. It seems, however, that they are either in the end stages of development or are commercially available, which means that we have probably seen all that this class of lenses has to offer. Nevertheless, they are still not without their limitations. Surgeons are constantly urged to select patients very carefully for multifocal IOL implantation and to then manage the expectations of that patient in order to increase the chances of a successful implantation.

While refractive multifocal lenses are proven to provide good intermediate vision, excellent distance vision and 100% light transmission, they fail to provide good near vision. Meanwhile diffractive multifocal lenses offer excellent near vision, very good distance vision but not so good intermediate vision.

"I began mixing & matching multifocal lenses this year
and have seen good results. This was very
surprising to me because I had many doubts
at the beginning. Unexpectedly my patients
feel good, really good"

It has, therefore, been hypothesized that the combination of the advantages of these two multifocal IOL technologies would allow surgeons to fully meet patients' needs, in terms of near, intermediate and distance vision under different light conditions. According to researchers, the processing of two different types of images is completely accepted by the patient and the brain, hence the mix and match concept (whereby a refractive IOL is implanted in the dominant eye and a diffractive multifocal IOL in the non-dominant eye) has been accepted by some surgeons as a feasible treatment modality.

"This year I performed my first mix and match case and, in my opinion, it is the best option that we have available to us today that helps us resolve the problems linked to the loss of accommodation in pseudophakic eyes. I do, however, believe that we are still waiting for the best solution to come along," conceded Dr Franchini. "Using these lenses has forced me to make a few changes to my surgical technique; I pay more attention to the tunnel construction and location in order to avoid inducing astigmatism, and I perform a smaller capsulorhexis to avoid any anterior lens postoperative movements," added Dr Franchini.

"I began mixing and matching multifocal lenses this year and have seen good results. This was very surprising to me because I had many doubts at the beginning. Unexpectedly my patients feel good, really good," remarked Carlos Vergés, MD, PhD.

Christoph Faschinger, MD on the other hand, is not convinced by the multifocal lenses and instead argues that surgeons do not know exactly how the patient, particularly the older patient, will adapt to the lenses. "Nobody knows how the capsular bag reacts when healing/sealing, moving forward or backward and changing refraction. If these lenses are so perfect, why does the community of cataract surgeons not implant them in the majority of patients?" questioned Dr Faschinger.

Although all experts agreed that multifocal IOLs have come a long way, they admitted that their popularity would be somewhat short-lived. In short, everybody is waiting with baited breath to see if the new generation of accommodating lenses can render many other IOLs obsolete.

Accommodating lenses could render all others obsolete

"I don't expect any further improvements to be made to multifocal lens design because, basically, everything that can be offered in terms of design and optics, is already available. Meanwhile, development of accommodating lenses continues and I sincerely believe that implantation of these lenses will become common practice in the next five years, completely replacing multifocal IOLs," predicted Dr Alió.

No one can argue that, although multifocal lenses effectively provide a wide range of vision, nothing is better than restoring true accommodation. Although the current generation of dual optic accommodating IOLs is better than its predecessors, Dr Alió believes that they have yet to make their mark and further development is still necessary before they achieve market dominance. "In my opinion, implantation of the current models of dual optic accommodating IOLs is cumbersome and these lenses, in some cases, simply provide similar accommodation to the partial accommodating IOLs. Variability is an issue in all of today's available accommodative lenses, either simple or dual optics. I remain to be convinced," he said.

Professor Dick disagrees. He feels that the latest generation dual-optic Synchrony lens (Visiogen), which is undergoing FDA and European trials, has demonstrated superb long-term results so far. "I didn't honestly expect this because I feared lenticular opacifications between the two lenses, which would then be tricky to treat, but this was not the case," he said.

"Variability is an issue in all of today's
available accommodative lenses, either
simple or dual optics. I remain
to be convinced"

According to Professor Dick, although the two lenses are made from silicone and although a little fibrosis is notable around the capsulorhexis rim after long-term implantation, the capsules are "crisp and crystal clear", even after three years. "Our mean accommodative amplitude after three years now with this lens is 1.8 and, with regards to side effects, none of these eyes required a YAG capsulotomy after three years," he confirmed. According to Professor Dick, this lens presents a viable option for refractive and presbyopia correction.

In addition, Dr Kuchynka admits that he has been surprised by the accommodating IOL Tetraflex (Lenstec) and claims that this is one of the exciting new technologies for presbyopia correction.

In contrast, Dr Faschinger referred to a recent study published by Oliver Findl, MD and Christina Leydolt, MD, in which three types of accommodating IOLs were compared following a meta-analysis of peer reviewed studies: 1CU (HumanOptics), BioComFold (Morcher), and AT-45 Crystalens (eyeonics).¹ Overall, Findl and Leydolt found that improvements in near visual acuity were moderate or non-existent in accommodating IOL-implanted eyes compared with controls and they felt that more evidence-based medicine was required to prove the benefit of accommodating focus-shift IOLs.

"We ourselves took histological sections of ciliary bodies from different age groups and found marked differences: there are wonderful muscles in young and few in elderly people but there is a significantly greater amount of connective tissue in old people, so it's not the lens alone that ages. How then can an 'accommodative' IOL work when the ciliary body is weak or not functioning anymore?" argues Dr Faschinger.

Although the excitement surrounding innovations in accommodating IOLs is not resonated by everyone, one thing is certain: if a lens is developed that can safely and effectively restore accommodation in presbyopic patients, cataract surgery will witness one of the biggest breakthroughs of this century.

Aspheric lenses failed to win the hearts of surgeons

Aside from the toric, multifocal and accommodating lenses, the impact made by the aspheric lenses has been less than spectacular. Because they are not customized to an individual's asphericity, some question whether a small gain in contrast sensitivity translates into a real improvement in quality of life for elderly patients. "I would not consider them as premium lenses, although some surgeons might think that they deserve this title. Rather I would consider them as standard lenses," admits Dr Alió.

"Admittedly, aberration-correcting lenses have been important, particularly in cataract patients who have previously received corneal refractive surgery. These lenses have been effective in compensating for the positive aberrations of the cornea," added Dr Alió.

Although the aspheric IOLs have failed to excite as many surgeons as their manufacturers had hoped, nothing can compare with the disappointment felt by the developers of the angle-fixated phakic IOLs. Specifically, the Vivarte/GBR (Ioltech) and ICARE (Corneal Laborotaries) lenses, which have now been withdrawn from the market because of safety concerns pertaining to endothelial cell loss.

"How then can an 'accommodative'
IOL work when the ciliary body
is weak or not functioning
anymore

"The angle-fixated phakic IOLs have been very disappointing. To me, their withdrawal from market was a horror story," said Professor Dick. "First, they rose like a star. Everyone was happy and started implanting the lenses. Then, just three years on, the star disappeared. Despite the manufacturers' attempts to improve lens material and design, the lenses were removed from the market because of poor endothelial cell results and keratoplasties. This was a disaster for the patient and for the doctor," noted Professor Dick.

Notwithstanding the highs and lows experienced by the IOL industry this year, exciting developments are on the horizon. Research and development is moving in the right direction and it is hoped that, in time, one clear winner will emerge in the race to develop the perfect IOL type.

Microincision cataract surgery: has bimanual had its day?

When considering surgical technique in cataract surgery, a consensus will probably never be reached on what the best method is. One of the major driving forces behind improving techniques, however, has undoubtedly been the prospect of reduced incision size.

When bimanual microincision cataract surgery (MICS), a term created by Dr Alió in 2001,² first graced cataract surgeries some years ago, many felt that it marked a turning point in the way the technique would be performed forever. Indeed, in some ways it did in that surgeons were finally able to create very small incisions. However, despite the enthusiasm, several years on, bimanual MICS accounts for less than 10% of cataract surgeries. Surgeons faced new issues with bimanual MICS, including sub-optimal infusion, wound leakage, thermal injury, anterior chamber instability and turbulence. Importantly, IOL development had still not reached that of cataract surgery instruments; no IOLs were available that could be implanted through a sub 1.5 mm incision.

Today, there has been little change. Although IOL technology is progressing towards the bimanual MICS ideal, many surgeons feel disappointed by the complications that have been associated with the technique so far.

"I do believe that bimanual phaco has represented one of the most important innovations in cataract surgery during the last decade. Despite this, I have stopped performing it in my routine cases, rather I reserve it for select cases only," admitted Dr Franchini. He now opts to perform microcoaxial surgery, which combines the principles of coaxial surgery with those of bimanual MICS to yield a technique that is simple to perform in standard cases and is associated with far fewer complications. As with most cataract surgeons, Dr Kuchynka also abandoned the bimanual technique in favour of microcoaxial surgery through a 2.2 mm incision.

"2007 certainly witnessed a change in the way cataract surgery was performed, not only with regards to the implantation of premium lenses, but thanks to new phaco machines with better ultrasound delivery systems and better fluidics control, there was definitely a trend towards microcoaxial and microincisional surgery," said Dr Vergés.

In fact, thanks to some recent innovations in instrumentation, coaxial microincision cataract surgery (CO-MICS; Oertli Instruments) has allowed surgeons to perform coaxial cataract surgery through incisions of between 1.6 and 1.8 mm. As a result, surgeons can enjoy the benefits of bimanual's small incision size and coaxial's stable anterior chamber.

Accommodating IOLs could spur a bimanual MICS revival

Dr Alió has successfully implemented MICS technology into his practice by introducing the acrylic, aspheric and multifocal Acri.LISA 366D MICS IOL (Acri.Tec), the toric microincision IOLs from the same company and Bausch & Lomb's new microincision lens MI60. "Surgeons are not happy to enlarge bimanual MICS incisions to accommodate the currently available lenses. I am, however, certain that companies, such as Acri.Tec (now supported by the marketing prowess of Zeiss) and Bausch & Lomb will develop lenses that are small enough to be implanted through these microincisions. As such, I believe they will push the market towards bimanual microincision practice," predicted Dr Alió.

Dr Franchini agrees. He believes that microincision coaxial surgery has reached its final stage of evolution and he also feels that, once IOLs are developed that can be implanted through sub 1 mm incisions, the practice of bimanual phaco will become the gold standard.

Dr Faschinger, on the other hand, characterizes himself as a conservative cataract surgeon, who does not try new products, instead he prefers watchful waiting whilst admiring all new inventions. He also concedes that the little money available to his University precludes him from taking on the latest in IOL and phaco technology. In particular, he voiced his admiration for a recent study performed by Dr Rupert Menapace, in which he examined the efficacy of posterior optic buttonholing (POBH) in 500 eyes through a primary posterior capsulorhexis (PPCCC) to preserve full capsular transparency and its potential as a routine alternative to standard in-the-bag implantation of a sharp-edged IOL.³ Dr Menapace was able to successfully and safely perform surgery and avoided secondary cataract formation, leading him to predict that POBH might become a routine alternative to standard in-the-bag IOL implantation. "I admire innovative surgical techniques such as Dr Menapace's. In addition, I visited a high volume surgeon in France recently. He performed perfect surgeries, implanting a foldable lens through a 2.2 mm incision simply by bringing the tip of the injector to the beginning of the tunnel and using a spatula in the paracentesis to counteract. I do, however, question the advantage afforded by a 2.2 mm incision over a 2.5 mm cut. Does 0.3 mm really make a clinical difference?" Dr Faschinger questioned.

The pressure is on for the lenses of tomorrow

Overall it seems clear that IOL advancements will shape the future of cataract and perhaps refractive surgery in the next few years. Surgical techniques are becoming more refined, less invasive and simpler, now the search goes on to find the lenses that can complement the package.

"My advice to industry would be to work to restore accommodation, not multifocality, and to continue to improve microincision techniques and devices. I expect, in the next five or ten years, that we will be restoring accommodation through microincisions," predicted Dr Alió.

Dr Alió recommends that we look out for the NuLens (NuLens Ltd.) accommodating IOL, which is currently undergoing investigation. He is also following progress with the new Crystalens, in the hope that some of the problems with the previous model have now been addressed. In the shorter term, Professor Dick suggests that we keep an eye on the Light Adjustable Lens (LAL; Calhoun Vision), which is also under investigation. This lens allows the surgeon to adjust the IOL power once the eye has healed, the aim being to customize power predictably to achieve optimal vision after cataract surgery without the need for glasses.

"The angle-fixated IOLs
have been very disappointing. To me
their withdrawal from market
was a horror story

Dr Alió also feels that diagnostic equipment will continue to improve in 2008. "We will be making objective assessments based on light scattering and on the intraocular performance of the natural lens and IOLs," predicts Dr Alió. According to Dr Alió, this improved instrumentation will be made more readily available moving into 2008, which will allow surgeons to make more accurate assessments and judgements. "Simply speaking, I can foresee an instrument that indicates to us which IOL to implant. These instruments will pay for themselves because the decisions that we make will be based on a much more solid base," he added.

Dr Faschinger hopes to implant a lens that is coated in antibiotic in the future, he would also like to see the development of technology that continuously monitors IOP whilst an IOL is in situ.

"At the beginning of the 90s, when we began working with an erbium-laser for cataract surgery, someone ask me what the dream was of a young anterior chamber surgeon for the end of the century. I told them that the dream was to one day perform cataract extraction through a very small incision and then to refill the capsular bag with an injectable lens in order to preserve accommodation. Well today, almost 20 years on, I think that the first part of this dream has been reached and the second part is on the horizon," reflected Dr Franchini. "The information that we have seen from companies leaves us hoping that the second part of my dream is not too far off, if not in 2008, then shortly afterwards," he added.

"If I had to invest in something today, I would invest in accommodation through microincisions. This will completely replace all technologies and lenses that we use today," concluded Dr Alió.

References

1. O. Findl & C. Leydolt.

J. Cataract Refract. Surg.

March 2007;33(3):522-527.
2. J.L. Alio, J.L. Rodriguez-Prats, A. Galal. MICS (Microincision Cataract Surgery). Highlights of Ophthalmology International, Miami, USA 2004.
3. R. Menapace.

J. Cataract Refract. Surg.

June 2006;32(6):929-943.

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