Eyeworld

EW CATARACT 42 November 2017 Presentation spotlight by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer choosing an EDOF is that it must be within one line of the BCVA that you get with a control monofocal lens. The second is that at the 20/30 level of vision, you have to have 0.5 D more of defocus than you have with a monofocal lens. It is interest- ing that a monofocal lens has about 0.75 D of defocus at the 20/30 level, and that means that the EDOF has to have 1.25 D. The third criterion is that 50% of patients have to be better than 20/30. The Tecnis Sym- fony EDOF IOL [Johnson & Johnson Vision, Santa Ana, California] fulfills these criteria," he said. Symfony EDOF outcomes According to a study that compared 62 patients who got Symfony lenses and 73 patients who got monofo- cal lenses, the amount of defocus at the 20/30 level was almost 1.0 D, exceeding the limit by almost a factor of two, and well over 50% of the patients had 20/30 vision. 2 The study also showed that the peak of the binocular defocus curve at 6 months was within two letters of the monofocal lens. According to Dr. Holladay, an important characteristic of the Sym- fony IOL may be its ability to reduce chromatic aberration. "All corneas have a similar amount of chromatic aberration. The cornea has positive chromatic aberration, which means that it bends blue light more than red. That difference in the human eye is about 1.25 D. Lenses with add that we generally use with dif- fractive bifocal lenses. The 3.0 D add will have bigger halos by a factor of two, compared to the 1.5 D add, and the 2.25 D add will be somewhere in between. EDOF IOLs will give better intermediate performance, less light scatter, smaller halos, and no 'dip' between distance and intermediate vision." Dr. Holladay explained that all IOLs with an emmetropia refrac- tion provide good distance vision (6 m/20 feet). Intermediate vision involves spectacle adds from +1.5 D (66 cm/26 in) to +2.00 D (50 cm/20 in), and near vision has more than one possible distance setting but is generally a spectacle add from +2.5 D to +3.00 (33 cm/13 in). "With an aspheric monofocal IOL, we can achieve the diffraction limit of the human eye of 20/10 visual acuity. An EDOF IOL's limit will be one or two lines less (20/12 or 20/16) in exchange for intermediate vision," he said. "With a diffractive bifocal lens that has two focal points, near and far focus, when you look at distance, you see that the near focus has defocused by the amount of the add. Therefore, a 3.0 D lens and a 4.0 D lens, in terms of their add, will have different sized halos directly proportional to the add." According to the American Academy of Ophthalmology Task Force consensus statement for EDOF IOLs, there are certain criteria for EDOFs. 1 "The first criterion for different distances, while minimiz- ing visual side effects, according to Jack Holladay, MD, MSEE, FACS, clinical professor of ophthalmology, Baylor College of Medicine, Hous- ton, who spoke on the topic at the 2017 ASCRS•ASOA Symposium & Congress. Perspective with other lenses "In the past, our presbyopic lens op- tions were accommodative IOLs and multifocals. Now there is a new IOL technology," Dr. Holladay said. "The way that you can think about EDOF IOLs is fairly simple. EDOF is similar to a 1.5 D add in the spectacle plane, compared to the 2.25 D and 3.0 D What EDOF IOLs have that others don't EDOF IOLs offer better intermediate performance and less light scatter than monofocal IOLs and smaller halos than multifocal IOLs E xtended depth of focus (EDOF) IOLs are currently in high demand because they offer patients new solutions to their visual needs that heretofore monofocal and multifocal options could not. The elongated focus associated with EDOF IOLs minimally affects peak resolution, providing clear vision at A monofocal aspheric IOL will have a single point of focus. Using diffractive optics, it is possible to "extend" the point of focus to be the same over a specified distance. The extended focus cannot be as perfect as a single focus, but must be no worse than one line compared to the monofocal. A cohort of patients are defocused from +2.0 D to –3.0 D and the average acuity recorded. In this example, the best corrected VA is about 0.2 lines less (or one letter), which is not significant. The blue region indicates the additional intermediate and near vision with the EDOF IOL. Source: Jack Holladay, MD, Extended depth of focus (EDOF) IOLs Eric Donnenfeld, MD, explains the differences between EDOF and conventional multifocal IOLs.

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