The Low Down on Multi-focal Intra Ocular Lens (IOLs) Or Is It the Let Down?
A big topic in cataract surgery has been about the use multifocal and toric Intra-ocular lens (IOLs) as an alternative to the proven mono-focal IOLs for lens replacement following one’s cataract removal. So, “the results are great”, “patients are happy”, physicians earn more, and the intraocular lens manufacturers make billions, Too good to be true, well partially, at least the latter two are true with physicians earning more while the IOL manufactures make billions.
Most of the published data on multifocal IOLs has been in non-peer-reviewed studies that overwhelming supports these types of lenses. The manufactures of these IOLs invest a lot of money and resources on “studies” and marketing to convince the ophthalmologist and patients to use their products. It is important in your research that you thoroughly review the financial disclosures of the authors of these articles, publications and websites.
The facts are multifocal IOLs have higher risk of undesirable visual disturbances and potential for increased complications associated with their use than do mono-focal IOLs. Multifocal IOLs are known to cause adverse problems, such as reduced contrast sensitivity vision, increased visual aberrations, halos, and intolerable glare, plus increased complications from required IOL exchange operations (Maria A. Woodward, June 2009 Volume 35, Issue 6).
Patient with multifocal IOLs have a disproportionately higher number of complaints (John C. Hagan III, December 13 2009) including; diplopia (double vision), uncomfortable binocular vision, glare, halos causing the inability to drive at night, loss of contrast sensitivity expressed subjectively by need for more light during reading and blurred far vision, and photophobia (light sensitivity) to such a degree that IOL exchange was deemed the only solution. Several studies show this rate of IOL exchange at 7% (Maria A. Woodward, June 2009 Volume 35, Issue 6), and is on the increase as more patient are convinced to have a multifocal type IOL (Mamalis N, 2008; 34(9)).
An IOL exchange requires another operation in which the eye has to be reopened and the multifocal IOL has to be cut into pieces within the eye in order to remove it followed by replacement with a proven mono-focal IOL. The success rate of replacing a multifocal IOL using the bagin-the-lens technique is not 100% but estimated to be at only 70%. This additional surgery has added risk, complications and expense and downtime for patient. The main perioperative complication was vitreous prolapse necessitating anterior vitrectomy in 23% of eyes (Marie-José Tassignon, Ellen Bartholomeeusen, Jos J. Rozema, Sien Jongenelen, & and Danny G.P. Mathysen, 2012).
The potential problems of reduced contrast sensitivity and dysphotopsias associated with multifocal IOLs, possibly requiring IOL exchange, are difficult for a patient to appreciate before undergoing surgery. Moreover, surgeons cannot predict preoperatively which multifocal lens patients are going to experience “debilitating” problems postoperatively (Wilkins MR & Group, 2013;120).
Why are there so many draw backs with multifocal IOLs? It is in the design, as multifocal IOLs are made up of several concentric rings of varying optical power, each of which refracts (bends) incoming light bringing it into focus at different points simultaneously. Therefore the images projected onto the retina whether close, intermediate, or distance will never be in 100% focus with patients that have received a multifocal IOL. The theory behind the multifocal design is to split certain percentages of focus between distant, intermediate, and near. For example, 75% distant, 25% for intermediate/near. The modification to the eyes optical system by a multifocal lens prevents images from ever being focused 100% at any distance even with glasses or contact lens. Because of the different focus points the lower quality of vision is described as “waxy”. The only solution to restoring the eyes optical system back to 100% in focus is surgery to remove the multifocal lens and replace it with a mono-focal one.
The implantation of multifocal IOLs are either contraindicated or associated with added visual difficulties in individuals with potential for macular problems, glaucoma, and diabetes mellitus with diabetic retinopathy or in patients with previous refractive surgery (Rosa Braga-Mele, 2014; 40). Other conditions such as retinal dystrophies (retinitis pigmentosa), irregular astigmatism, zonnular dehiscence, and optic nerve disorders are also contraindications to a patient receiving a multifocal IOL (Rosa Braga-Mele, 2014; 40).
Additionally, in an interview, Dwayne K. Logan, M.D. with Atlantis Eye Care stated that multifocals are contraindicated in patients who have any type of corneal disease, or opacification of the cornea. They would not do well in patients who have conditions that might affect the transmission or processing of light back to the brain—for example, a stroke, some type of atrophy from glaucoma, or a type of genetic disorder that affected the retina, optic nerve, or the brain (Passut, 2011).
The reason for contraindications in using multifocal IOLs in patients with these conditions is the out of focus dispersion of light along the visual axis. Patients with low-contrast sensitivity due to different pathologies would be disabled by multifocal lens dispersion.
Perhaps one of the biggest problems with multifocal IOLs is not yet to be realized and seems to be completely ignored. As individuals age their chance of developing glaucoma, macular degeneration, and/or diabetic retinopathy statistically increases. Glaucoma, macular degeneration, and diabetic retinopathy in that order are the second, third, and fourth leading causes of blindness in the world with cataract being the first. Cataract can be “cured” with surgery unlike the other 3 conditions which need treatment for life. Patients receiving multifocal implants today may not have been diagnosed with condition(s) where implantation of a multifocal IOL is a real bad idea. We cannot predict who will develop medical or eye conditions that make multifocal lens a bad choice. Unfortunately this will result in an epidemic of substandard vision in those patients with multifocal implants than if high definition mono-focal lens had been implanted. Stating, “if this happens one can do a lens exchange” is not that simple because the complications of intra-ocular implant exchange surgery increase exponentially if not performed within several months of the original cataract operation. Individuals receiving multifocal IOLs run the risk of not possibly achieving or enjoying the best possible vision later in life as compared to mono-focal IOL recipients.
The multifocal dispersion of light rays accounts for the glare, halos causing the inability to drive at night as well as loss of contrast sensitivity typically experienced as a loss of some clarity in low light situations such as reading a menu in the a dark restaurant or driving after dark.
A night driving performance study was conducted to assess functional performance differences between multifocal and mono-focal IOL patients. Binocular visual performance was measured while driving under low visibility conditions such as night driving and with headlight glare conditions. This study measured night driving visibility distances and evaluate driving safety in terms of critical stopping sight distance. In general, mean night driving visibility distances for detection and identification of text, warning and pedestrian targets was lower for multifocal subjects than for mono focal subjects. The mean percent loss in visibility detection and identification distances was nearly a 25% loss for most distances, even in city roads with visual clutter and background interaction for the multifocal group as compared to the mono-focal group (Proposed DFU for the Tecnis Multifocal Foldable Acrylic IntraOcular Lens, http://www.accessdata.fda.gov/cdrh_docs/pdf8/p080010c.pdf).
In another study, led by Fuxuzng, M.D., researchers set out to compare how patients with bilateral multifocal IOLs stacked up against those who were implanted with mono-focal IOLs. Forty-three patients received either multifocal IOLs or mono-focal as mono-vision. At the 3-month mark, investigators found that the multifocal IOL group did slightly better in terms of bilateral uncorrected distance and near vision, but the difference was not statistically significant. The mono-vision group experienced better intermediate vision, which allowed them to use computers with significantly less difficulty than their multifocal counterparts. Mono-vision scored higher in terms of satisfaction, fewer complaints, and less out-of-pocket costs. The mono-vision patients achieved comparable distance and near vision, but without the risk of disturbing visual symptoms sometimes associated with multifocal IOLs ( Fuxiang Zhang, M.D. J Cataract Refract Surg 2011; 37:446–453 Q 2011 ASCRS and ESCRS).
“Basically, the trade-off for a slight increased chance of spectacle-independence is reduced visual quality and a 1 in 20 chance of a further operation with some morbidity attached,” as stated by Gerald Sutton, MBBS, MD, from the Sydney Medical School Foundation, professor of corneal and refractive surgery.
In addition, Medicare and private insurers will not pay the costs of multifocal (or toric IOLs) nor the associated services that exceed the charges for a conventional mono focal IOL. The cost of using these multifocal lenses is twice the price of implanting the latest generation of mono-focal lens.
Short term or long term, the multifocal IOL may not be the best option.
So what is a safer option for patients desiring the added benefit of achieving reduced spectacle dependency with their cataract procedure?
Mono vision or blended vision using the newer high definition mono-focal IOLs at the time of cataract surgery have proven to reduce dependency on spectacles while at the same time not adding the risk of unwanted visual disturbances associated with multifocal IOLs.
The goal is to target one eye for near or intermediate vision and the other eye for distance. This method is the safest method to provide a cataract patient with lessened dependency on glasses or contact lens for the rest of their lives.
Cataract patients can upgrade their cataract procedure to a refractive procedure without additional risk and complications associated with using multi focal IOLs.
Ask us about the benefits of our LaHayeSight™ Advanced and Premium Laser-Enhanced Cataract procedures if you are interested in lessened dependency on spectacles and contact lens without the worry of multifocal IOL associated problems.
I do not put intra-ocular lens implants that have to be removed.
Why play Russian roulette with one’s eyesight- choose LaHayeSight™.
Leon C. LaHaye, M.D.
Sources and Bibliographies
Maria A. Woodward, MD,J. Bradley Randleman, MD, R. Doyle Stulting, MD, PhD Dissatisfaction after multifocal intraocular lens implantation Journal of Cataract and Refractive Surgery June 2009 Volume 35, Issue 6 Pages 992-997
John C. Hagan III, MD, Kansas City, Mo and Michael J. Kutryb, MD, Titusville, Fla and Michelle Stephenson Multifocal IOLs have a disproportionately high number of patient complaints Discover Vision Centers of Kansas City Dec 13, 2009
Mamalis N, Brubaker J, Davis D, Espandar L, Werner L. Complications of foldable intraocular lenses requiring explantation or secondary intervention – 2007 survey update. J Cataract Refract Surg. 2008; 34(9):1584-1591.
Marie-José Tassignon, MD, PhD, FEBO; Ellen Bartholomeeusen, MD, FEBO; Jos J. Rozema, MSc, PhD; Sien Jongenelen, MD; and Danny G.P. Mathysen, MSc IOL Exchange for Patients Unhappy With Multifocal IOLs Cataract & Refractive Surgery Today Europe September 2012 p 22-24, 80
Wilkins MR, Allan BD, Rubin GS, et al; Moorfields IOL Study Group Randomized Trial of Multifocal Intraocular Lenses Versus Monovision After Bilateral Cataract Surgery Ophthalmology. 2013; 120:2449-2455
Rosa Braga-Mele, MD, FRCSC, David Chang, MD, Steven Dewey, MD, Gary Foster, MD, Bonnie An Henderson, MD, Warren Hill, MD, Richard Hoffman, MD, Brian Little, MD, Nick Mamalis, MD, Thomas Oetting, MD, Donald Serafano, MD, Audrey Talley-Rostov, MD, Abhay Vasavada, MD, Sonia Yoo, MD, Multifocal intraocular lenses: Relative indications and contraindications for implantation J Cataract Refract Surg 2014; 40:313–322 Q 2014 ASCRS and ESCRS
Proposed DFU for the Tecnis® Multifocal Foldable Acrylic Intraocular Lens P9-11 http://www.accessdata.fda.gov/cdrh_docs/pdf8/p080010c.pdf
Fuxiang Zhang, M.D. J Cataract Refract Surg 2011; 37:446–453 Q 2011 ASCRS and ESCRS).