New generation of IOLs moves toward combinations of advanced technologies

Will an aspheric/toric/blue-light-filtering multifocal be the IOL of the future? Surgeons talk about what is available and what may be coming soon.

The latest generation of IOLs offers a range of technologies for surgeons to choose from, taking the best qualities of its predecessors and refining the most successful of these traits. Future developments may include combinations of IOL technologies, providing more choices for surgeons and patients, experts suggest.

Surgeons familiar with the latest IOL technologies spoke with Ocular Surgery News about their preferences among the currently available lenses and about how they see the IOL market developing.

IOL technologies that have been introduced in recent years include aspheric designs that neutralize patients’ natural spherical aberration and a new generation of multifocal designs that exceed the performance of previous generations.

In addition to briefing OSN about the pluses and minuses of each of these technologies, surgeons we interviewed spoke about mixing these lenses to give patients the benefits of more than one technology at a time. They also speculated about possible combinations of technologies in a single lens in the future.

“Eventually, these beneficial technologies will be incorporated into almost all lenses, and surgeons will have more choices,” Frank A. Bucci Jr., MD, told OSN.

Aspheric lenses

There are now at least three IOL models on the U.S. market with aspheric designs that aim to counteract the natural spherical aberration present in the human eye. The Tecnis IOL, now available in both silicone and acrylic materials from Advanced Medical Optics, was the first aspheric IOL on the market. It was followed by the Alcon AcrySof IQ acrylic lens and the Bausch & Lomb SofPort AO. Each lens has a different aspheric design and corrects different amounts of spherical aberration.

Aspheric IOLs have surfaces that change curvature from the center to the periphery of the lens, said Farrell C. Tyson, MD, “so that when the light rays come into that lens, they all come into focus at one point.”

“Each one does it a little bit differently,” he continued. “The Tecnis has that change of curvature on the front surface. The Alcon IQ has it on the back surface. And the Bausch & Lomb has it on both the front and back.”

Dr. Tyson said the Tecnis corrects the most spherical aberration and is therefore suitable for a majority of the population, and the Alcon AcrySof IQ and Bausch & Lomb AO are better suited for patients with less spherical aberration.

Richard L. Lindstrom

Correcting the eye’s inherent spherical aberration helps to enhance distance vision under mesopic conditions, said Richard L. Lindstrom, MD, OSN Chief Medical Editor.

The evidence for the benefit of aspheric IOLs is strong enough, Dr. Lindstrom said, that he has switched to using aspheric IOLs rather than conventional spherical IOLs for almost all monofocal IOL implantations.

Uday Devgan, MD, FACS, OSN Cataract Surgery Section Member, said, “In 99.9% of eyes, it does not make sense to use a traditional design IOL which induces a lot of positive spherical aberration.”

“In the same way that right now every IOL has a coating that blocks ultraviolet light, I think in the very near future – the next couple years – every IOL, or nearly every IOL, is going to have an aspheric design of one type or another,” Dr. Devgan said.

Dr. Tyson agreed that aspheric lens designs will more than likely become a standard in the IOL industry and in ophthalmic practice. He cited the Food and Drug Administration’s approved labeling for AMO’s Tecnis IOL, which states that the lens increases night driving safety.

“When the FDA states that a lens is increasing your reaction time by 0.5 seconds, and the third brake light was mandated by the federal government on cars because it increased your reaction time by 0.3 seconds, that’s pretty strong evidence to implement these lenses,” he said.

Alcon’s aspheric IOL, the AcrySof IQ, is promoted as being thinner than other aspheric IOLs at 0.61 mm, providing blue light filtration for better color perception and protection, and maintaining the familiar AcrySof one-piece acrylic design.

The IQ is the standard monofocal implant for Richard E. Braunstein, MD, who told OSN he switched to that lens about 1 year ago after seeing the manufacturer’s data. He has since conducted his own study comparing postoperative aberrations in patients with the IQ lens and conventional spherical IOLs.

“We found a statistically significant reduction in higher-order aberrations in the eyes of patients who were corrected with the IQ IOL when compared with traditional conventional IOL,” Dr. Braunstein said. “We were expecting to see that, but it’s one thing to see it in the laboratory and another thing to see it in your postoperative patient.”

Edward J. Holland, MD, who also implants the AcrySof IQ, explained why the IQ has a built-in –0.2 µm of spherical aberration.

“The IQ has built into it technology to deal with corneal asphericity as well as the lens asphericity,” he said. “The Alcon IQ has built in –0.2 µm of spherical aberration, which results in approximately a +0.075 µm asphericity in the operative eye. The reason why this target was chosen is that studies show that a target of around +0.075 µm to +0.1 µm spherical aberration provides peak visual performance.”

According to Bausch & Lomb, the company’s SofPort AO (for Advanced Optics) imparts no spherical aberration postoperatively, as opposed to the negative spherical aberration created by other companies’ aspheric IOLs.

“I consider the SofPort AO a ‘universal’ lens, which can be used in any case, as it does not induce any aberration,” Dr. Lindstrom said in an e-mail interview.

The neutral spherical aberration of the SofPort AO carries certain advantages, Dr. Devgan said.

“It decreases, of course, the spherical aberrations of the eye as compared to a traditional IOL,” he said. “As well, it may give increased depth of field because it leaves a mild amount of corneal spherical aberration intact.”

Bausch & Lomb also manufactures the Akreos AO, a hydrophilic acrylic aspheric IOL. That lens is in use in Europe but is not currently approved in the United States.

“The other acrylic IOLs in the U.S. market are hydrophobic, and therefore they have slightly different properties,” Dr. Devgan said. Because the hydrophilic lens is not yet available to U.S. surgeons, differences in the behavior of these two types of lenses in the hands of American surgeons have yet to be seen, he said.

Multifocal lenses

The two multifocal lenses now approved for use in the United States are the AcrySof ReSTOR apodized diffractive IOL from Alcon and the ReZoom IOL from AMO. Surgeons interviewed for this article expressed different preferences regarding the two lenses. Some said they prefer to mix the two technologies, implanting one in each eye of their patients.

Dr. Braunstein said the ReSTOR is his multifocal lens of choice.

Frank A. Bucci Jr.

“I’ve chosen it for the fact that it incorporates blue-light filtering,” Dr. Braunstein said. “It’s an acrylic lens, which I believe is the desired lens material. It gives patients more reading vision than the other multifocal lens implant, and the clinical trial data supports the highest percentage of patients who are spectacle independent after bilateral lens implantation.”

Dr. Bucci said he thought the AcrySof ReSTOR was the answer to problems he had experience previously with AMO’s Array lens. Patients with the ReSTOR IOL experienced fewer halos and had better reading ability than with the Array, he said. The ReSTOR lens has provided patients with good near vision, especially in bright light, and fewer unwanted photic phenomena at night, Dr. Bucci said.

Dr. Tyson said the ReSTOR lens works best for patients who require better near vision than intermediate vision.

“ReSTOR works better in your patient who has dense cataracts who wears flat-top bifocals because they’re used to seeing things up close,” Dr. Tyson said. “They’re not used to having intermediate vision.”

On the other hand, he said, the AMO ReZoom multifocal IOL may work better in patients who are used to no-line progressive spectacles that provide intermediate vision.

“A lot of my patients are more of that progressive no-line bifocal crowd, and they’re used to having a range of vision,” Dr. Tyson said. “I find that the ReZoom does better because it has more intermediate, but it still has very good near.”

The ReZoom is an upgraded and redesigned version of AMO’s earlier multifocal, the Array. This newer version provides good near vision in moderate light, excellent intermediate vision and excellent distance in bright light, users said.

“In greater than 90% of my presbyopic patients,” Dr. Tyson said, “I find that ReZoom works better [than ReSTOR] because I have a more active and young presbyopic demographic” that demands good intermediate vision.

Mixing and matching

Given the strength of the ReSTOR IOL’s near vision and the ability of the ReZoom to provide intermediate focus, some surgeons have taken to mixing and matching them to retain the pros of each and counterbalance the cons.

The ReSTOR-ReZoom combination is “my first choice,” Dr. Bucci said. “That’s what I do probably 19 out of 20 times, and I’m achieving almost 100% spectacle independence with that.”

He said the lenses are complementary, each one stronger in the areas where the other is weak. With the two technologies combined, patients can achieve “reasonably good vision at near, intermediate and far” and manageable light phenomenon at night, he said.

“It just happens that the two strengths of the ReSTOR, which are less light phenomena at night and stronger reading, just happen to be the two weaknesses of the ReZoom,” Dr. Bucci said.

Dr. Lindstrom agreed. “By mixing, you can get seamless vision, distance to near,” he said.

Dr. Lindstrom explained that the brain adapts to receiving different images from the two lens technologies.

“Neural adaptation is real and continues for years,” Dr. Lindstrom said. “My multifocal patients out 5 or more years have all adapted to their new optical system and never complain of night vision symptoms or glare/halo.”

He added, “Early studies suggest patient acceptance and function are high. I believe this will become the dominant approach.”

Dr. Bucci said he presented a study at the 2006 American Society of Cataract and Refractive Surgery meeting showing that patients’ vision was statistically significantly better with the ReSTOR-ReZoom combination than with ReSTOR implanted bilaterally.

“In my opinion, we should look at the two lenses as a pair,” Dr. Bucci said. “We should look at the lenses as a visual system.”

Dr. Tyson was less enthusiastic about mixing multifocal IOL technologies. He said it may be appropriate in some cases, but if the surgeon picks the right patient and the right lenses, bilateral implantation of the same technology can be sufficient.

“I’ve mixed and matched and had mixed and matched results,” Dr. Tyson said. “I think it works better to do bilateral instead of mixing and matching. You’re giving the brain the same image so you’re going to get better cerebral summation.”

Combining technologies

The next phase of IOL development, according to surgeons interviewed for this article, will be for manufacturers to continue combining their successful technologies into one IOL package. As Alcon now combines its blue-light filtering technology with asphericity in its AcrySof IQ, other manufacturers will begin to combine features.

Farrell C. Tyson

AMO has done this with the Tecnis Multifocal IOL, combining its aspheric lens design with a multifocal technology. That lens is in use in Europe but not yet approved by the FDA.

“I think you’re going to start seeing a blending of the wavefront technology into the multifocal world,” Dr. Tyson said.

Dr. Bucci added, “There will be some learning curve there, and we’ll see what benefits there may be. We’ll head in that direction, for sure.”

“I think it would be good to try and harness both [aspheric and multifocal] technologies together,” Dr. Braunstein added.

To take the combining process a step further, Dr. Braunstein said he hopes to see an aspheric multifocal toric IOL.

Robert J. Cionni, MD, suggested that could happen in the near future.

“Multifocal, toric, aspheric – it would be a lot of things together but would allow you to give the patient, within the limit of measurement errors, the complete package,” Dr. Cionni said.

Dr. Bucci proposed that companies should manufacture pairs of multifocal lenses that can work together in a patient’s two eyes – one for near and intermediate vision and the other for intermediate and far vision.

“I don’t think one lens is going to do all three things [near, intermediate and distance] really well,” Dr. Bucci said. “The doctor will always have the choice to take the near-intermediate from one pair and use the distance from another pair because they just happen to work better.”

Future of accommodating IOLs

Physicians interviewed for this article also said they look forward to the development of an accommodating IOL that provides 6 D to 7 D of accommodation. Some said they are skeptical that this goal is within reach any time soon.

“Because prior claims have been made by so many different manufacturers, I’m really a little bit skeptical,” Dr. Devgan said. “Everything that’s said, I take with a grain of salt.”

The IOL surgeon’s mantra is to “undersell and overdeliver to his patients,” Dr. Devgan said, and future accommodating IOL designs must follow that guideline.

“The accommodating IOLs must surpass the surgeons’ expectations,” he said. “The problem is, I think a lot of the manufacturers overpromised what their products could do and somewhat underdelivered.”

Rather than wait for something that is out of reach, some surgeons said they would rather focus on technologies already on hand.

“To get a super-duper accommodating lens that’s going to give you excellent distance, excellent intermediate and excellent up-close, accommodate freely like our 20-year-old lens, I don’t know if that’s right around the corner like some people think it is,” Dr. Bucci said. “While they’re pursuing the great and perfect accommodating lens, we’ll continue to improve the multifocal technology.”

Smaller incisions

There has been much interest in the past several years about the possibility of operating through smaller cataract incisions, less than 2 mm in length. Technologies for both bimanual microincision cataract surgery and coaxial microincision surgery have been developed by the manufacturers of phacoemulsification equipment. What is still missing is a lens to go through those incisions.

“Our current selection of lenses can’t really get through these incisions,” Dr. Tyson said. “So the next thing is how to deliver these lenses through smaller incisions.”

He said companies are devising ways to package current lenses tighter. He predicted many companies would move to pre-loaded injectors to achieve insertion through smaller incisions and to minimize manipulation of the IOL by technicians.

Dr. Devgan said semi-preloaded IOL inserters, such as the Easy Load Injector for the SofPort AO, may become more important as surgeons try to insert IOLs through smaller incisions.

Other companies have come up with IOLs that fit through smaller incisions, but none of them have reached the U.S. market.

“Many manufacturers are coming out with IOLs, especially in Europe, that go through sub-2-mm incisions and I think that’s a neat move toward the future,” Dr. Devgan said. But he expressed concerns about the value of using incisions much smaller than the standard 2.6-mm phaco incision.

“As the inflow-outflow devices become smaller, it becomes slower and slower to do the surgery and more difficult,” Dr. Devgan said. “If the cataract is like a milkshake, and you’re trying to suck it out of the eye using a really, really tiny cocktail straw, it’s going to take a long time. Relative flow decreases exponentially with smaller sized tubing, as Poiseuille’s equation tells us.”

Dr. Devgan said surgeons are also unwilling, for the sake of a smaller incision, to sacrifice the quality of vision and the protection against posterior capsular opacification that have become standards in modern IOL design.

“There’s an order in which things are important, and I think smaller incisions are near the bottom of the list,” Dr. Devgan said. “Surgeons now are spoiled. We want everything, but we’re not willing to give up great aspheric optics, excellent biocompatibility and a low PCO rate in order to achieve a somewhat smaller incision.”

For more information:

• Frank A. Bucci Jr., MD, can be reached at Bucci Laser Vision Institute, 158 Wilkes-Barre Township Blvd., Wilkes-Barre, PA 18702; 570-825-5949; fax: 570-825-2645; e-mail: buccivision@aol.com.
• Richard E. Braunstein, MD, can be reached at The Edward S. Harkness Eye Institute, Columbia University College of Physicians and Surgeons, Department of Ophthalmology, 635 W. 165th St., Box 39, New York, NY 10032; 212-305-3339; fax: 212-305-0900; e-mail: reb10@columbia.edu.
• Edward J. Holland, MD, can be reached at 580 South Loop Road, Edgewood, KY 41017; 859-331-9000; e-mail: eholland@fuse.net. Dr. Holland is a consultant for Alcon.
• Robert J. Cionni, MD, can be reached at 10494 Montgomery Road, Cincinnati, OH 45242; 513-984-5133; fax: 513-984-4240; e-mail: rcionni@cincinnatieye.com. Dr. Cionni is a consultant for Alcon.
• Farrell C. Tyson, MD, can be reached at 4120 DelPrado Blvd., Cape Coral, FL 33904; 239-542-2020; fax: 239-542-0704; e-mail: tysonfc@hotmail.com.
• Richard L. Lindstrom, MD, is the Chief Medical Editor of Ocular Surgery News. He is in private practice at Minnesota Eye Consultants, 710 E. 24th St., Suite 106, Minneapolis, MN 55404-3810; 612-813-3600; fax: 612-813-3660; e-mail: rllindstrom@mneye.com. Dr. Lindstrom is a paid consultant for Advanced Medical Optics, Alcon and Bausch & Lomb.
• Uday Devgan, MD, FACS, is an OSN Cataract Surgery Section Member, an assistant clinical professor at the Jules Stein Eye Institute at UCLA and in private practice in Sun Valley, Calif. He can be reached at 9375 San Fernando Road, Sun Valley, CA 91352; 818-768-3000; fax: 818-504-4463; e-mail: devgan@ucla.edu. Dr. Devgan has no financial interest in the products mentioned in this article and does not accept funds or honoraria for his involvement in ophthalmic consulting.

• Katrina Altersitz is an OSN Staff Writer who covers all aspects of ophthalmology.