January 2019

CATARACT

Device focus
Trifocal IOLs provide near, intermediate, and distance vision


by Michelle Stephenson EyeWorld Contributing Writer

Although not yet approved for use in the United States, trifocal IOLs are providing near, intermediate, and distance vision to patients in Europe and Canada

Because multifocal IOLs do not provide optimal intermediate vision, surgeons often mix and match IOLs to achieve the best vision at all three distances.
“We will either implant an extended depth of focus (EDOF) IOL or a lower add multifocal in the dominant eye, and we will implant a higher add bifocal in the non-dominant eye in an attempt to get all three distances,” said Vance Thompson, MD, Sioux Falls, South Dakota.
In contrast, trifocals can be implanted in both eyes because they provide vision at all three distances. Three trifocal IOLs are currently approved for use outside of the United States: the AT LISA (Carl Zeiss Meditec, Jena, Germany), the AcrySof IQ PanOptix (Alcon, Fort Worth, Texas), and the FineVision (PhysIOL, Liège, Belgium).
According to Thomas Neuhann, MD, Munich, Germany, the basic principle of two diffractive step-widths combined to provide distance, intermediate, and near foci is used by all of these lenses. “The Alcon lens uses a particular diffractive construction to obtain an intermediate range from 1.2 to 0.6 m. The intermediate focus is not created at the expense of the light distributed to the distance and near foci but makes light otherwise lost, such as in bifocal diffractive lenses, available and usable for the intermediate focus,” he explained.
John Berdahl, MD, Sioux Falls, South Dakota, noted that the adoption rate of trifocals outside of the United States has been tremendous. “In many places, it’s the go-to lens type. It is about defocus curves and trying to provide as much of a continuous range of vision as possible, while avoiding unwanted side effects like positive dysphotopsias,” he said.

Advantages and disadvantages

The advantage of trifocal IOLs is that they provide vision at all three distances. “No currently available single lens provides distance, intermediate, and near vision,” Dr. Berdahl said. “Trifocals would give each eye the ability to see well at all three distances, which I suspect will allow for more forgiveness if we aren’t exactly on target.”
“Because all multifocal IOLs divide the incoming light into more than one focus, the effect of the light in ‘out of focus’ images reduces the contrast of ‘in focus’ images,” Dr. Thompson said. “If a patient is looking at a distance, he or she will have near and intermediate images that are not in focus, which can reduce contrast sensitivity and modulation transfer function (MTF). MTF is a useful optics measure of true or effective resolution, since it accounts for the amount of blur and contrast over a range of spatial frequencies. As a result, unwanted visual phenomena, including glare and halo, can occur. One of the main reasons that multifocal IOLs are being implanted with growing frequency is because the optics have been optimized to the point that patient satisfaction is much higher than multifocal implants of 10 or 20 years ago. There is a much lower incidence of glare and halos. Twenty years ago, they were 0.1% of the implants I placed, and now multifocals are 40% of the implants that I use because of how happy they make my patients who desire to be spectacle independent. I have been in trifocal FDA trials in the United States, and I think they’re going to be a game-changer for us, too.”
However, there are certain patients for whom Dr. Thompson would be cautious about recommending any implant that splits light, whether it is an EDOF or multifocal lens. Any eye pathology that scatters light in an unsophisticated way can degrade the sophisticated optics of modern-day multifocals or EDOF lenses. “For example, dry eye, epithelial basement membrane dystrophy, or a corneal irregularity, such as keratoconus, should be treated before implantation of a trifocal. If we cannot decrease the higher order aberration state of the cornea and tear film to an acceptable level, we don’t want to add a multifocal implant to that optical system. We also like to make sure the patient has a healthy macula, and that’s why doing an OCT is so important. Of course, we also need to be able to enhance the patient’s cornea with PRK or LASIK to optimize the optics to plano. That is why a corneal refractive workup needs to be a part of any premium implant evaluation. We don’t want to have a patient with residual refractive error postoperatively who we can’t enhance with the laser because they have a topographic irregularity or other contraindication to a laser fine tune. We want to find these issues preoperatively and do a monofocal IOL in these situations. But as long as the tear film, cornea, and macula are healthy and the posterior capsule is clear after implant surgery, whether it took a capsulotomy or not, and the refractive error is near plano with or without an enhancement, this adds up to extremely high patient satisfaction,” Dr. Thompson said.
Dr. Neuhann agreed. “I would not use them in patients with additional contrast lowering and/or light dispersion conditions, such as corneal guttata, pronounced dry eye, prior corneal laser vision correction with imperfect contrast sensitivity, and/or light phenomena,” he said.
He advised extreme caution with prior low myopes. “Their lifelong excellent uncorrected near vision and, consequently, expectation is a great danger for disappointment with the near vision with such lenses,” he said.

Pearls

Dr. Thompson explains to patients that achieving the desired outcome is a four-step process.
First is the implantation of the advanced trifocal, bifocal, or extended depth of focus implant.
Second, 3 months later, if there’s any residual refractive error, an enhancement is performed using PRK or LASIK.
Third, if the posterior capsule develops opacity a YAG laser is performed. More YAGs will be performed because a subtle posterior capsule opacity can degrade the optics of the implant more quickly than a monofocal implant.
Fourth is neural-adaptation. “After the implant is in, the refractive error minimized with a fine tune or the patient ended up plano, and the capsule lasered, patient satisfaction at a month is quite high but even higher at a year,” Dr. Thompson said. “I tell patients that we’re embarking on a year-and-a-half journey together and that they’ll most likely experience some impressive improvements along the way, but at the end of that year and a half, they’ll have some of the world’s most advanced optics in their eyes to help them do a lot without glasses at multiple distances for the rest of their life. The patients that go into it with this attitude do beautifully.”
Dr. Berdahl agreed. “I think we’re seeing the continued improvement of presbyopia-correcting IOLs in an iterative fashion because of all the experience that we’ve had with them, and it’s great to be part of an innovative profession that’s getting better every day,” he said.

The future

Dr. Neuhann said he doesn’t see a future for bifocals. “When a multifocal is the option, use a trifocal. I do not see a place for bifocals anymore. Trifocals offer everything a bifocal can plus the intermediate vision at no extra expense. Realize—and make patients realize—that with presbyopia, everything is a compromise. We have the privilege to have multiple compromises available, with different advantage/disadvantage profiles, to choose from. But we must never forget that they are all compromises. We do not have the option that everyone wants, namely, ‘back to youth’ vision with accommodation,” he said.

Editors’ note: Dr. Berdahl has financial interests with Alcon, Johnson & Johnson Vision (Santa Ana, California), RxSight (Aliso Viejo, California), and Bausch + Lomb (Bridgewater, New Jersey). Dr. Thompson has financial interests with Alcon, Johnson & Johnson, and Carl Zeiss Meditec. Dr. Neuhann has no financial interests related to his comments.

Contact information

Berdahl
: john.berdahl@vancethompsonvision.com
Neuhann: prof@neuhann.de
Thompson: vance.thompson@vancethompsonvision.com

Trifocal IOLs provide near, intermediate, and distance vision Trifocal IOLs provide near, intermediate, and distance vision
Ophthalmology News - EyeWorld Magazine
283 110
283 110
,
2018-12-31T11:08:56Z
True, 1