EyeWorld India June 2015 Issue

June 2015 18 EWAP FEATURE New tools in the cataract surgeon’s toolbox by Vanessa Caceres EyeWorld Contributing Writer AT A GLANCE • Extended depth of focus and extended range of vision IOLs are a newer type of IOL that extend the focal point of the lens. They are designed for cataract surgery patients who have presbyopia. • These lenses are used in Europe and around the world but have not yet received approval in the U.S. • Study results so far show that glare and halos are equivalent to monofocal IOLs. • Extended depth of focus, extended range of vision lenses provide advantages for presbyopia patients, await more studies in the U.S. and abroad Extended depth of focus, extended range of vision lenses provide advantages for presbyopia patients, await more studies in the U.S. and abroad A s surgeons continually aim to boost refractive outcomes, some think that extended depth of focus and the first extended range Mahipal SACHDEV, MD Chairman, Medical Director & Senior Consultant Ophthalmology, Centre for Sight B-5/24 Safdarjung Enclave, New Delhi-110029 Tel. nos. (91-11) 41644000, 45738888 drmahipal@gmail.com T he introduction of the extended range of vision IOLs is an interesting breakthrough in our endeavor to provide good functional vision without glasses to our presbyopic and cataract patients. Cataract surgery is becoming a refractive procedure with the introduction of femto-lasers for incisions, rhexis and lens fragmentation, and high quality IOLs. However, multifocal lenses still have issues such as glare, haloes and loss of contrast as well as less than optimum intermediate vision, an important requirement for daily activities. The available accommodative lenses give about 1 D of near correction which is adequate for intermediate work but not for near. As I understand in this interesting technology , what comes across distinctly clear is that this lens is on the same platform as the Tecnis 1-piece with all the inherent scoring points. The exciting feature of Tecnis Symfony as I appreciate it is the extended range or depth of focus in which objects remain in focus without sacri cing acuity or contrast. Enumerating the attractive selling points of the Symfony as I understand it is the incorporation of the diffractive optics and the high abbé number which has vastly improved chromatic aberration and thus obviated the lack of contrast, a glaring problem for multifocal IOLs. Furthermore, the low refractive index of this IOL material causes less re ectance, thus reducing dysphotopsia and glare from light scatter, a feature of multifocal IOLs currently on the market. In addition is the echelettic pro le of the diffractive zone which is so designed to shift the wavelength of light and cause further increased depth of focus. The night myopic shift is dramatically improved with the reduced chromatic aberration. Even if we are half a diopter off target as analyzed by Dr. Frank Goes, we are still in the sweet spot because of the extended range of focus and hence the refractive concerns as in multifocal IOLs are less. However, there appears to be a fallback in this technology as regards not striking the 100% reading ability without glasses but again the extended range of vision in the entire defocus curve is promising and should handle this limiting feature. Having said that, one can play with the option of micromonovision to the patient’s advantage. Hopefully, patients with these lenses will be happier than multifocal IOL patients and have smooth vision with minimal side effects. I would watch these lenses and their long- term results with keen anticipation and expect them to get more widely used bringing cataract surgery outcomes closer to a refractive procedure. Editors’ note: Dr. Sachdev is a consultant for AMO, Alcon (Fort Worth, Texas), Zeiss (Jena, Germany), Bausch + Lomb (Bridgewater, NJ), and Allergan (Irvine, Calif.). Views from Asia-Paci c The Tecnis Symfony has an elongated focal point, giving the wearer a continuous, full range of vision. Although the lens has diffractive gradings, it creates only one image on the retina, not the two images characteristic of multifocal IOLs. Source: Abbott Medical Optics of vision IOLs, all available outside of the U.S. at this time, may be the right fit for presbyopic patients who want refractive cataract surgery. The design of extended depth of focus IOLs appears to improve on any downfalls associated with multifocal IOLs. “The lenses redistribute the rays from a singular focus in a monofocal IOL to a range of foci, minimally affecting the peak resolution, or best focus,” said Jack T. Holladay, MD, MSEE, clinical professor of ophthalmology, Baylor College of Medicine, Houston. “Without being a true multifocal IOL, [extended depth of focus lenses] extend the focal point out through various mechanisms,” said Douglas D. Koch, MD , professor and the Allen, Mosbacher, and Law chair in ophthalmology, Cullen Eye Institute, Baylor College of Medicine. “One mechanism is to create some form of spherical aberration that increases depth of focus. The second is a little extension of multifocality but with compensation of chromatic aberration. By doing this, it increases clarity and depth of focus.” “The new class has one focal point, but it’s spread over a long area so there’s a broad focus over approximately 2 diopters,” said Eric D. Donnenfeld, MD , clinical professor of ophthalmology, New York University Medical Center, New York. Dr. Donnenfeld is involved with U.S. Food and Drug Administration (FDA) clinical trials of the Tecnis Symfony (Abbott Medical Optics, AMO, Abbott Park,