Growing variety of IOLs heightens selection challenges, chances of success
Currently available IOLs offer a wide range of options and increasing opportunities for personalized selection. The FDA approval in August 2019 of Alcon’s AcrySof IQ PanOptix trifocal IOL, the first of its kind in the U.S., further enriched the market. Although the perfect lens that satisfies all needs without compromise is not yet there, and careful case-by-case evaluation is still required, the chances of satisfying patients are much greater than in the past.
“IOL exchange is now significantly less frequent, and patients are happier. However, getting to know your patients, spending time talking to them, setting expectations and making sure they are aware of potential downsides are still key,” OSN Technology Board Member Kathryn M. Hatch, MD, said.
First thing to bear in mind is that not everyone is a candidate for presbyopia-correcting lenses, and this choice should not be forced upon patients.
“Some people don’t mind using spectacles, and reading or computers are not their priorities. I operated on a pilot recently, and he was certainly not a candidate for multifocal IOLs,” she said.
Even before chair time, preoperative evaluation is crucial to assess whether patients have the anatomic and functional prerequisites to consider a presbyopic option.
“True that with the newer technologies we experience less dysphotopsia, but it is extremely important to optimize the ocular surface by treating any dry eye and meibomian gland dysfunction, and be aware of conditions that masquerade as dry eye, such as epithelial basement membrane dystrophy. I rule out patients with irregular astigmatism and those with macular pathologies,” Karolinne M. Rocha, MD, PhD, said.
No more gaps in vision
Presbyopia-correcting IOLs available in the United States include the Crystalens AO (Bausch + Lomb), the Tecnis multifocal +4.0 D ZMB00, followed by the +2.75 D and +3.25 D options (Johnson & Johnson Vision), and the AcrySof IQ ReSTOR +3.0 D and +2.5 D (Alcon). In 2016, the FDA approved the Tecnis Symfony extended depth of focus lens, and in 2019, the PanOptix. Some of these lenses are also available in a toric option, including the latest EDOF and trifocal models.
“We were struggling with the earlier models of multifocals, as we had gaps in vision, particularly with intermediate vision. Patients were able to read but not to see the computer, and we know how important it is nowadays to have good computer vision. The newer models of lower add multifocals were an improvement but then patients had to wear reading glasses, and so we were mixing and matching, putting an intermediate add in one eye and a stronger add in the fellow eye. Trifocal technology is really solving this problem because it gives all three steps. We don’t need to mix and match as often now,” Hatch said.
Careful preoperative assessment, however, remains mandatory. Patients must be aware that they will experience some degree of mild halo and glare and accept it as a price to pay for spectacle-free vision.
“I offer the PanOptix lens to people who are motivated to get rid of spectacles and spend a lot of time on the computer as well as reading,” Hatch said.
The Symfony EDOF or Activefocus also addresses intermediate vision, but it is best for people who do not mind using spectacles for reading.
“Patients are still experiencing dysphotopsias with EDOF IOLs; however, the symptoms are typically tolerable when encountered. Dysphotopsias cannot be completely avoided because we are still dealing with a multifocal optic. I consider this lens in post-refractive eyes in motivated patients, if the topography looks good, because it can be more forgiving,” Hatch said.
The Symfony EDOF has been a cornerstone addition in OSN Technology Board Member Rocha’s planning for personalized vision.
“If patients want to be spectacle-independent, I implant the Symfony in the dominant eye and a new-generation, low add multifocal, the Tecnis ZLB00, in the fellow eye,” she said. “The Symfony is a pupil-independent diffractive EDOF that provides high quality, high contrast, high light transmission and chromatic aberration correction. So, in patients who don’t mind the idea of using readers, it may be worth implanting it bilaterally. When I do bilateral Symfony, I usually target a near plano. I do the dominant eye first, wait for about 2 weeks, and if the patient is 20/20 and J2 to J3, I implant the Symfony in the contralateral eye. It is such a high-quality lens that sometimes, because of binocular summation, patients can gain one more line and read J1. But we cannot promise that; we must say clearly that what the lens is best for is distance and intermediate vision.”
The Symfony is also available in the ZXT toric model, as is the PanOptix.
“We can offer them both for astigmatic correction,” Rocha said. “Again, if patients with significant astigmatism want to be sure to be spectacle-free, I go for the PanOptix toric model and implant it bilaterally. A mix-and-match personalized vision approach is more difficult in astigmatic patients with what we have in the U.S. right now.”
The science of psychometrics
A cloud-based online questionnaire that patients fill out at home helps surgeons make a well-thought-out decision based on which IOL options best meet patient needs and expectations.
“We are very good at biometrics. We are submicron precise in our ability to measure the retinal cells with OCT and the cornea with topography, but what is important for selecting an IOL is not so much what is happening between the orbital bones but what is happening between the patient’s ears — in the patient’s mind. What we are not very experienced at is the science of psychometrics, which is understanding the patient’s needs, desires and what is likely to work for them,” OSN Cataract surgery Section Editor John A. Hovanesian, MD, FACS, said.
MDbackline’s Visual Profile Report, created by Hovanesian with the input of Vance Thompson, MD, David F. Chang, MD, Eric D. Donnenfeld, MD, Richard L. Lindstrom, MD, and others, is a psychometric system in many practices across the U.S.
“Patients see first some educational material, which helps them get over the fear of cataract surgery, seeing it rather as an opportunity to change their life and make a choice of what their vision will be in the future. We tell them there are lens options that cost extra but are worth considering because they will affect the rest of their life,” Hovanesian said.
The second step is answering a questionnaire. Patients are asked what their current visual challenges are, such as glare at day or night, or difficulty reading small print, TV captions or books in dim light conditions. They report on their visual habits, such as driving at night, using the computer or looking at fine details, and whether they have already tried contact lens solutions, such as monovision or multifocality. Finally, they estimate how important it is for them to be spectacle-free at the various distances and if they would accept glare in exchange for spectacle independence. They are also asked to report on other complaints such as dry eye and on any previous eye surgery.
“When the patient comes back to the office, we have a report that has already been generated automatically by the system. We can look at each section analytically, and we have an estimate of the likelihood that the patient will choose a presbyopia-correcting IOL and be satisfied with it. The estimate is calculated by a proprietary software that utilizes the data of hundreds of previous cases. We get an idea of what kind of presbyopia-correcting IOL solution we should consider and what we should be cautious of,” Hovanesian said.
The main concern with presbyopia-correcting IOLs is dysphotopsia, and although the outcome cannot be entirely predicted, this psychometric system helps look for warning signs, ruling out bad candidates for diffractive technologies.
“For patients who are more intolerant to glare, we can choose either a monofocal or a toric lens. If they are more inclined toward distance vision and don’t care too much about wearing reading glasses, they will be happy with these options. Otherwise, if they prefer to be spectacle-free, you can talk to them about monovision,” Hovanesian said.
Psychometrics combined with biometrics together provide a more complete diagnostic picture.
Verifying tolerance of dysphotopsia
European cataract surgeons have an even greater variety of IOLs to choose from. Florian T. Kretz, MD, uses a personalized vision approach based on the patient’s daily habits, the lighting of their workplace, the motivation to be spectacle free at various distances and, importantly, their current experience and tolerance of dysphotopsia.
“It is very important to ask patients if they already see halos and glare around light sources because cataract patients and myopic patients have some degree of dysphotopsia anyway, and this might be comparable to what they will experience after implantation of an IOL. I use a simulator, and the key question I ask is, ‘Do you already experience dysphotopsia, and if you do, can you continue driving or do you have to stop on the way?’ It is often a matter of acceptance, as for many of the consequences of the aging process,” Kretz said.
Patients who continue driving despite glare and halos and who do not mind wearing glasses for reading are good candidates for a diffractive lens that covers the intermediate range, such as an At Lara (Carl Zeiss Meditec) or xact Mono-EDoF (Santen), which are not yet available in the United States. If patients cannot accept halos, Kretz chooses a rotational asymmetric profile that produces hardly any dysphotopsia or goes for a pinhole IOL.
Classification made simpler and clearer
Even though the field of IOLs is wide, the choice can be made more simple by classifying IOLs based on optical profile.
“There are multifocal diffractive lenses, with several fixed foci, and multifocal diffractive trifocal lenses, with three foci, created by a diffractive ring structure. The other options are the refractive lenses, like the bifocal rotational asymmetric Oculentis, with two foci, and the IC-8 (AcuFocus) pinhole IOL,” Kretz said.
EDOF, he said, is a marketing name and not a separate category because any presbyopia-correcting IOL is an EDOF in the sense that it creates an enhanced depth of focus.
“Making EDOF a separate category does not make sense because many EDOF IOLs have multiple foci. We need to go back to what the optical profile is. In this perspective, the Tecnis Eyhance (Johnson & Johnson Vision) is an aberration-modified profile. The xact is a diffractive low add. It was licensed as monofocal, but on the optical bench it is still multifocal because it has rings creating two foci. It is very simple: If we go back to optical physics and describe the profile, it will be much easier for ophthalmologists to understand. It is the commercial nomenclature and marketing of companies that confuse people a lot,” he said.
U.S. colleagues can look forward to more trifocal IOLs in the near future, with different light distributions for even better intermediate vision in dim light.
“There are companies starting their first trials on hydrophobic platforms,” Kretz said.
Mono-EDOF IOLs will be another interesting addition. Among them, the Eyhance is a pure monofocal optic that relies on aberrations to elongate the focus to an extended intermediate range. The xact Mono-EDoF has four diffractive rings but a through focus modulation transfer function curve that is similar to that of a monofocal lens. The rings are larger, so they give true intermediate vision to 66 cm, but also no more dysphotopsia than a monofocal. Both IOLs provide excellent distance and good intermediate vision without side effects.
“Johnson & Johnson with the Eyhance, and later with the Tecnis Synergy, as well as Santen with the xact, are working their way to the U.S. market. Santen is working at it with AVS, their subsidiary company in California, and the process should not be long because the hydrophobic material of the xact platform is already licensed in the country,” he said.
In March, Alcon launched its new AcrySof IQ Vivity in Europe, and at the end of February, the lens obtained FDA approval.
“This is also a kind of mono-EDOF, providing extended range of vision with a non-diffractive design,” Kretz said. “Having this lens available is going to be very exciting for U.S. surgeons because for the first time they will be able to mix and match different optics with different light distributions based on the same platform and same material.”
As the lens gains credibility, it could fill an important technology gap, Hovanesian said.
“In Europe, the Vivity IOL has already received a warm reception as a non-diffractive lens for providing distance and intermediate vision that promises little or no unwanted visual side effects. For highly discerning patients and those whose eyes are not ‘perfect enough’ for a diffractive multifocal, this lens could be a very welcome entrant to the U.S. market as well,” he said.
For special cases
The asymmetric IOLs of the Oculentis family are now available on a hydrophobic platform, and the company is working on a new model with an approved hydrophobic material so that it could enter the U.S. market.
“Patients with low acceptance for dysphotopsia and close to normal angle kappa are perfect for these lenses,” Kretz said.
The pinhole IC-8 is the ideal lens for patients with problems that make them unsuitable for most presbyopia-correcting IOL solutions, such as high corneal aberration, irregular astigmatism and no acceptance for dysphotopsia.
“Also for post-refractive patients, where IOL calculation is difficult. It is a very forgiving lens for these patients and gives them a good depth of focus. That is what they are used to and expect after cataract surgery,” Kretz said.
“It is a good backup for all those cases where you feel uncomfortable with other optical principles. It is going to be very beneficial for U.S. colleagues when they get it, especially because they have a much higher number of patients who have had corneal refractive surgery with all profiles and highly aberrated corneas. They should really look forward to it,” he said.
“I am excited about what’s ahead. We always seek lenses with less dysphotopsia and lenses for difficult eyes like irregular astigmatism, glaucoma or macular degeneration. I am particularly looking forward to having the newer-generation non-diffractive EDOF lenses such as fully diffractive IOLs (Isofocal, PhysIOL), higher-order aspheric anterior surface designs (Eyhance) because it can be more forgiving, and we are waiting for the results of Alcon Vivity, which has two smooth surface transition elements on the anterior surface of the lens,” Rocha said.
Another lens she would like to have in the U.S. is the trifocal PhysIOL (FineVision).
“And we are still in quest of an accommodative IOL, which would be the perfect lens for all, with monofocal-like optics, no dysphotopsia and vision at all distances. Realistically, I think it would be more distance to intermediate, but it would still be perfect, without issues of night vision symptoms. It is the dream lens for which every single patient can be a candidate,” she said.
Hatch considers the RxSight Light Adjustable Lens (LAL) as an option that is raising interest and quite a lot of discussion.
“It could turn out to be the most accurate refractive procedure we’ve ever had,” she said. “And I also hope we will eventually be successful with accommodative IOLs because multifocality, no matter how advanced it is, can never be devoid of side effects. An accommodative lens would be a wonderful opportunity for all patients, including those with Fuchs’ dystrophy and other ocular pathologies.” – by Michela Cimberle
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- For more information:
- Kathryn M. Hatch, MD, can be reached at Massachusetts Eye and Ear Waltham, 1601 Trapelo Road, Suite 184, Waltham, MA 02451; email: email@example.com.
- John A. Hovanesian, MD, FACS, can be reached at Harvard Eye Associates, 24401 Calle De La Louisa, Laguna Hills, CA 92653; email: firstname.lastname@example.org.
- Florian T. Kretz, MD, can be reached at PVK Precise Vision GmbH, Hoerstkamp 7, 48431 Rheine, Germany; email: email@example.com.
- Karolinne M. Rocha, MD, PhD, can be reached at Storm Eye Institute, Medical University of South Carolina, 167 Ashley Ave., Charleston, SC 29425; email: firstname.lastname@example.org.
Disclosures: Hatch reports she is a consultant to Johnson & Johnson and Carl Zeiss Meditec. Hovanesian reports he is founder of MDbackline and a consultant to Johnson & Johnson, Bausch + Lomb, Alcon and Carl Zeiss Meditec. Kretz reports he is a consultant to Carl Zeiss Meditec and receives honoraria from Bausch + Lomb, Rayner and Santen. Rocha reports she is a consultant to Alcon, Bausch + Lomb and Johnson & Johnson.
Click here to read the Point/Counter to this Cover Story, “Prospectively, which IOL would you choose for yourself if you were to have cataract surgery?”