Multifocal IOLs offer the potential to reduce spectacle dependence, but outcomes vary depending on optical design. Optimizing success and satisfaction depends on careful patient selection, thorough counseling, and good surgical technique.
Reviewed by Damien Gatinel, MD, and Nick Mamalis, MD
For patients seeking spectacle independence after cataract surgery or refractive lens exchange, implantation of a trifocal IOL is a better option than a lens with a bifocal optic or an extended depth of focus/extended range of vision design, according to Damien Gatinel, MD.
Whether using a bifocal or trifocal IOL, however, there are certain issues surgeons should consider in order to optimize outcomes and the likelihood of achieving satisfied patients, said Nick Mamalis, MD.
Reviewing the attributes of the different multifocal IOLs, Dr. Gatinel explained that relative to bifocal and extended depth of focus/extended range of vision designs, trifocal IOLs provide a more continuous range of uncorrected vision.
Furthermore, available evidence indicates trifocal IOLs deliver their benefit without increasing the risk of unwanted visual phenomenon.
“A bifocal IOL can provide good uncorrected vision at far and at near distances that are in the range of 30 to 45 cm, but they do not give good uncorrected vision for intermediate vision, which is important today for people who are working at a desktop computer, using a laptop, or reading a tablet,” explained Dr. Gatinel, assistant professor of ophthalmology, and head, anterior segment and refractive surgery department, Rothschild Ophthalmology Foundation, Paris.
Even lowering the add power of a bifocal IOL does not result in good intermediate vision because a “confusion focus” remains between the near and distance foci, he noted.
“Extended depth of focus and extended range of vision IOLs afford better intermediate vision than a bifocal IOL,” Dr. Gatinel said. “With these newer technologies, however, patients may still need to wear glasses for some near vision tasks.”
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Dr. Gatinel was involved in the design of the first trifocal IOL that became commercially available (FineVision, PhysIOL) in Europe in March 2010.
“The idea for this implant was born in my mind when I realized patients who were implanted with a bifocal IOL would thank me for their ability to read and drive without glasses, but they noted they still needed glasses with a low add for working at the computer,” he said.
In order to improve vision at intermediate distances, Dr. Gatinel designed an implant combining two bifocal designs-one for distance and near and other for distance and intermediate.
In addition, the optic incorporates apodization and step heights that maintain good distance vision. The lens is also pupil dependent so that contrast at distance is increased with the pupil is large and vice versa.
Currently, two other trifocal IOLs are also available in Europe, of which one features an optic design similar to that of the FineVision IOL (AT Lisa Tri 839mp, Carl Zeiss Meditec) while the other combines two diffractive gratings with a nonharmonic relation (Panoptix, Alcon Laboratories).
Dr. Gatinel noted that results of optical bench testing assessing the trifocal IOLs demonstrate their benefit for providing better intermediate vision compared with a bifocal IOL. Defocus curve findings in a French multicenter study evaluating patients implanted with the FineVision trifocal IOL are consistent with the optical bench results in showing that the trifocal design provides a continuous range of clinically useful visual acuity.
“The defocus curve shows more of a plateau rather than a trough between the distance and near visual acuities,” he said.
Data on visual quality measures and symptoms show that while contrast sensitivity is reduced with both bifocal and trifocal technology relative to monofocal IOLs, it is similar at near and distance comparing the two presbyopia-correcting technologies and better at intermediate with the trifocal IOL.
The potential for halos and starburst with trifocal IOLs has also been extensively studied and found to be similar to or less than that associated with bifocal technology, Dr. Gatinel said.
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“Our experience in clinical practice is that patients implanted with a trifocal IOL may mention they see halos,” he said. “However, these patients usually do not complain about visual symptoms and the number of individuals who say they cannot drive at night because of bothersome symptoms is very low.”
Nevertheless, surgeons implanting a trifocal IOL should warn patients about the potential for postoperative halos and glare, he noted.
Because trifocal IOLs are only available in countries outside of the United States, Dr. Mamalis noted that he lacks first-hand experience with these implants.
However, the considerations for achieving success with trifocal IOL implantation are similar in many respects to those pertaining to bifocal IOLs, said Dr. Mamalis, professor of ophthalmology, John A. Moran Eye Center, University of Utah, Salt Lake City.
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In summary, he advised surgeons to choose patients carefully and counsel them thoroughly so that they have realistic expectations regarding visual outcomes.
In addition, he emphasized the importance of obtaining accurate preoperative measurements, minimizing residual refractive error, and achieving good IOL centration.
If faced with a patient who is dissatisfied postoperatively, surgeons should try to identify and address potentially correctable problems.
“Ultimately, however, if you cannot make the patient happy, consider exchanging the multifocal IOL for a monofocal lens,” Dr. Mamalis said.
Implantation of multifocal IOLs should be approached with caution in people with certain personality types, professions, or vision needs, as these individuals may not tolerate the trade-offs inherent in multifocal optic technology, Dr. Mamalis suggested.
“People with type 1 personalities, anyone who is obsessive-compulsive, as well as lawyers, engineers, and people who do extensive night driving or working in dim-light conditions may be unhappy with the limitations of these IOLs, which include reduction in contrast and night-time visual symptoms,” he said.
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“That is not to say use of these lenses is absolutely contraindicated for these individuals,” Dr. Mamalis said. “Before proceeding to implant these lenses, however, surgeons would do well to think twice and counsel these patients thoroughly about the potential downsides.”
A comprehensive ocular examination is also critical because patients who undergo multifocal IOL implantation should have healthy eyes free of any sight-threatening pathology. Careful attention should be given to the condition of the ocular surface.
Dr. Mamalis recommended avoiding implantation in anyone with corneal scars or dystrophies and in patients with dry eye whose tear film abnormalities cannot be corrected through preoperative treatment.
“These patients will not do well because vision is degraded by tear film abnormalities and potentially will be further degraded by the lens,” he said.
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Macular pathology should also be identified preoperatively because it too degrades image quality, and so surgeons may consider performing OCT to identify abnormalities that otherwise may not be visible through the cataractous lens.
“Age-related macular degeneration and epiretinal membranes are relatively common in the population of older patients undergoing cataract surgery,” Dr. Mamalis said. “Epiretinal membrane can be treated preoperatively, but it first has to be detected, and that may be challenging looking through an opacified lens.”
He suggested that patients who have mild glaucoma that is well-controlled remain reasonable candidates for a multifocal IOL. However, Dr. Mamalis advised exerting greater caution in anyone with more advanced glaucoma.
Patient satisfaction after multifocal IOL surgery also depends on achieving good refractive outcomes, and so accurate biometry is critical as is astigmatic management. Dr. Mamalis noted that residual astigmatism exceeding 0.5 D or 0.75 D will considerably degrade image quality.
“Be careful to control your ametropic and astigmatic results when putting in a bifocal or trifocal IOL,” he said.
Proper lens centration is also critical for optimizing postoperative visual quality with multifocal IOL technology.
“Any significant decentration of the implant will result in a dramatic drop in quality of vision,” he said. “For that reason, if there are any complications intraoperatively that can affect lens centration and stability consider converting to a monofocal IOL.”
Information from studies that have investigated reasons for multifocal IOL explanation and patient dissatisfaction with multifocal IOLs reinforces the advice offered by Dr. Mamalis.
Data from an annually conducted ASCRS/ESCRS survey show that unwanted visual phenomenon, e.g., glare and optical aberrations, are the most common reasons for multifocal IOL explanation, followed by problems with dislocation and decentration.
The most common reasons for patient dissatisfaction are blurred vision with or without photic phenomenon and photic phenomenon in general, and the common etiologies underlying these complaints are residual ametropia and astigmatism, posterior capsule opacification (PCO), and large pupil size.
“These are all issues that interact with optical performance and accentuate potential problems with multifocal IOL technology,” Dr. Mamalis said.
Findings of other studies were similar in showing reasons for multifocal explanation or patient dissatisfaction included decreased contrast sensitivity, photic phenomena, blurred vision, anisometropia, and dislocation/decentration, as well as incorrect IOL power and excessive preoperative patient expectations.
“These data again underscore the need to counsel patients carefully about the outcomes and to beware of those who seem to want magic and are hoping for complete spectacle independence,” Dr. Mamalis said.
Although vision problems that are secondary to PCO can be addressed by Nd:YAG laser capsulotomy, Dr. Mamalis cautioned that if the patient remains unhappy after the procedure, lens explantation will be more challenging in the setting of an open capsule.
“Before performing capsulotomy, make sure first that the problem is caused by the PCO and not something else,” he said.
Damien Gatinel, MD
This article is based on presentations given by Dr. Gatinel and Dr. Mamalis during the 2015 meeting of the American Academy of Ophthalmology. Dr. Gatinel is a consultant to PhysIOL and holds a patent and proprietary interest in the FineVision trifocal IOL.
Nick Mamalis, MD
Dr. Mamalis is a consultant/advisor for companies that market IOLs.