Eyeworld

This CME supplement is supported by unrestricted educational grants from Alcon and Bausch + Lomb. Extended range of vision These lenses use 3 principle optical strategies to achieve the increased visual ranges: spherical aberration control; a diffractive optic not to provide multiple foci but to expand the single focal zone; and chromatic aberration control. Spherical aberration control is the same concept as the negative spherical aberration design cataract surgeons know from the Tecnis platform. This is designed to coun- terbalance the positive spherical aberration of the cornea. It's been well established over the years. This provides better contrast and better quality of vision. Diffractive optics on an IOL typically have created a second focal point, as that's how they've tradi- tionally been used. But by modify- ing the echelettes (the ridges), the lens can be engineered to create a single, elongated focal zone. Compared to a monofocal IOL, diffractive multifocals have slightly diminished image quality, but it is imperative to know the visual quality with a diffractive mul- tifocal lens relates to the multifocal- ity of the lens, not to the diffractive optic itself. The current iteration of lenses are actually bifocal, not truly multifocal, and that becomes an im- portant differentiation. As a group, we need look no further than profes- sional photographers to learn about optics. One of the most expensive lenses is the Canon EF400F4DO, a lens based on diffractive optics. Photographers use diffractive optics for chromatic aberration control. As light passes through a typical refractive lens, a prismatic effect creates the light dispersion. Chro- matic aberration occurs when light gets dispersed owing to the prismat- ic effect of IOLs. Some wavelengths of light are out of focus. Intraocular lens material properties can contrib- ute to the eye's baseline chromatic aberration. See Figures 1, 2, and 3 for differences between refractive, diffractive, and combination optics. The Symfony uses all 3 of these features: spherical aberration con- trol, expanded depth of focus with a diffractive optic, and chromatic aberration correction. A study com- pared the Symfony to a standard Tecnis monofocal IOL, using typical outcome measurements such as defocus, visual quality, patient satis- faction, and spectacle independence. Bilaterally implanted subjects fared much better with the Symfony. 4 When these patients are in front of a phoropter, even after 6 clicks (1.5 D of over-minusing power) they were still reading at 20/20. Even af- ter 10 clicks patients still read 20/40. That's an extraordinary increase in the range of focus compared to a standard monofocal IOL. Comparing the Symfony to a standard Tecnis, there's very good uncorrected distance with both lenses and very good best corrected distance with both. 4 But distance- corrected intermediate vision was markedly better with the Symfony, and distance-corrected near vision was 20/30. These outcomes are sub- stantially better than standard IOLs provide. Perhaps the most interesting finding was that there was no differ- ence in glare or halos compared to a monofocal IOL. There were no spontaneous reports of glare and halo by the 3-month postopera- tive point, and 97% of the patients would choose the Symfony again. The new low-powered multifo- cals will emphasize intermediate and distance vision, and the new extend- ed range of vision IOLs will provide less optical compromise. These are going to be a significant addition to our armamentarium. Reference 1. ASCRS Clinical Survey 2014. Global Trends in Ophthalmology. Fairfax, VA: American Society of Cataract & Refractive Surgery, 2014. 2. Schallhorn, Steven. Impact of residual cylinder on patient satisfaction and quality of vision after premium IOL, 2013 ASCRS•ASOA Symposium & Congress. 3. Data on file, Alcon Laboratories. 4. Data on file, Abbott Medical Optics. Supported by an unrestricted educational grant from Abbott Medical Optics Discussion Dr. Lindstrom: I'm quite excited about the extended depth of focus lens. I think this might be able to create a new category that I might call premium mono- vision. Dr. Blecher, is this going to be a whole new opportunity? I usually do plano and –1.50 and while outcomes are acceptable, I personally don't charge patients for doing that. Dr. Blecher: This may give you the opportunity to provide those kinds of premi- um results to patients who don't have the means to opt for some of our out-of- pocket options. I'm excited that it's not going to be an either/or situation. We're going to have a wider range of lenses for the patients to give them better vision. Dr. Lindstrom: What impact do you think these new technology lenses are going to have on your practice? Dr. Dell: If we can reliably give patients 1.25 D or 1.50 D of additional near assistance without compromising their distance vision, it changes everything. If we use a little bit of defocus on top of that—maybe –0.50 D, –0.75 D of monovision, which most patients are not going to perceive—now we can give them extraordinary near vision. Also, the patients we are disqualifying from a typical multifocal because of other ocular disorders (early age-related macular degeneration) may be appropriate candidates for these lenses. Dr. Vukich: The extended range of vision lenses open up a whole new concept. We've talked about monovision and mini-monovision. I've heard this described as micro-monovision. A 0.50 D of difference between the eyes is tolerated by virtually everyone. Most surgeons don't use monovision for all patients because not everyone can handle it. Somewhere between 1.5 D and 1.75 D is the tipping point, but if we can minimize that to 0.50 D of mini-monovision or micro-monovision I think we've got a really good solution. Multifocality isn't going to go away, though. Multifocal lenses still provide the best near vision. I agree with Dr. Lindstrom's statement that intermediate is not what drives patient satisfaction, near vision is. That's what will drive patients to choose multifocals. Dr. Lindstrom: Over the years, I've been comfortable doing custom matching —different IOLs in each eye. I've found patients adapt well. I'm interested in what our cumulative experience will be with an extended depth of focus lens in one eye and the near dominant multifocal in the other versus mini-monovision. Are we going to be seeing more dissimilar IOLs in the two eyes? Dr. Dell: I think so. It's an underutilized technique. I think that's a very good strategy to implant expanded depth of focus lenses in the dominant eye and a multifocal in the non-dominant eye. It's going to take us a while to figure that out. We just evaluated how we schedule our cataract surgery, how patients present, and what we do from there. The overwhelming majority (82%) of my patients are scheduled one eye first, other eye to follow in a planned, sequen- tial, bilateral surgery. We're not waiting a year before scheduling second eye surgery. So it's logical that we can plan a mix and match approach as a natural consequence. Dr. Lindstrom: Yes, I call it "complementary intraocular lenses" when I talk to my patients. They seem to like that term.

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