Presbyopia correction with glasses is associated with reduced quality of life,1 and lens-based correction of presbyopia has become a routine aspect of cataract surgery,2 although it remains challenging. Cataract surgery has evolved into lens-based refractive surgery. Although nearly 76% of cataract surgeons in the US offer presbyopia-correcting lenses, according to the Market Scope Q4-2014 survey of US cataract surgeons, not all patients are good candidates for them and presbyopia-correcting intraocular lenses (IOLs) accounted for only 4.5 to 5% of all IOL procedures.3 One possible reason for this is high levels of patient dissatisfaction after implantation of presbyopia-correcting intraocular lenses.4
Until recently, two types of presbyopia-correcting IOLs were available: multifocal or accommodative, both of which have limitations. Multifocal lenses comprise diffractive optic lenses that split light between distance, intermediate and near. The user can only focus on one distance at a time, leaving the blur from the other focal points to sometimes cause photic phenomena such as halo and glare. Accommodative lenses are designed with some flexibility of movement that allows the optical portion of the IOL to move slightly forward upon contraction of the ciliary muscle. While they provide an expanded range of clear vision compared with conventional monofocal IOLs, they are less effective than multifocal lenses at near distance. As a consequence, ophthalmologists prefer to offer monovision with standard IOLs where the dominant eye is usually targeted for distance and the nondominant eye for the intermediate/near range.
Extended depth of focus (EDOF) IOLs are a new technology designed to allow for an extended range of sharp vision and a low incidence of halo and glare.5 These IOLs differ from multifocal lenses as they create elongated defocus curve peaks without the traditional bimodal or trimodal peaks seen with multifocal lenses, allowing a more continuous range of near vision instead of multiple points of focus.6 The TECNIS Symfony® EDOF IOL (Johnson & Johnson Vision, NJ, US) is the only EDOF IOL currently available. It received Food and Drug Administration approval in 2016 and has shown improved visual outcomes in a number of studies.7 The Symfony Toric IOL also allows the surgeon to mitigate the effects of astigmatism along with presbyopia, expanding the number of patients who can receive IOLs.8 Other IOLs are in development, including the IC-8™ small aperture IOL (AcuFocus, Inc., United States), which has received CE marking approval and is available in select European markets,9 and the WIOL-CF® (Medicem) polyfocal IOL.10 One disadvantage of the EDOF IOL is that the near-vision correction is not as good as a multifocal lens. Patients can typically see their dashboard or computer, but may need reading glasses for small print.
In a presentation at Hawaiian Eye, which was held on January 19–25, 2019, in Waikoloa, Hawaii, Sumit “Sam” Garg, MD, associate professor of ophthalmology and vice chair of clinical ophthalmology, University of California Irvine School of Medicine, gave tips for minimising patient dissatisfaction and optimising outcomes with EDOF IOLs. Dr. Garg began by highlighting the importance of understanding the visual outcomes of EDOF IOLs and matching them with patient needs and expectations.11 “I’m a big believer that there is no perfect lens out there and you really have to take the time out with your patient, personally, to really decide if this has the right optics for them,” he said.12 By asking patients about activities such as night-time driving, reading, working outdoors, etc., a physician can determine which IOL is more appropriate. Dr. Garg also explained that understanding defocus curves is important to understand where the lens has its sweet spots. The creation of defocus curves involves placing lenses in front of an eye while measuring the change in visual acuity that results from various amounts of refractive error.13
Dr. Garg emphasized the advantages of EDOF lenses over multifocals: “you don’t get two sweet spots, it doesn’t split light in the same way and studies show that you get a good tolerance to unexpected refractive surprises, and a better tolerance to residual errors,” he said. It is also important to take into account the patient’s starting point. “Are they a low myope? Are they 40 years old versus 80 years old? What are their needs?” Dr. Garg asked. He also looks for dominance in these lenses: “With the Symfony lens, I try to get as close to plano as I can in the dominant eye and in the nondominant eye you have options.”11,12
As the range of available IOLs expands, it can be difficult for a patient to understand their treatment options. Dr. Garg recommends using a visual simulator by Johnson & Johnson Vision. The simulator shows the patient what astigmatism looks like, as well as halos, glare, and spiderwebs, and shows how each of the TECNIS lenses will affect their vision. Johnson & Johnson also provide a toric calculator that can tailor IOLs to patient needs. According to Dr. Garg, “Being meticulous in your IOL calculations is important; really taking into account posterior corneal astigmatism has been a nice addition for us and on the J&J calculator there’s a way to select that or de-select it when managing patients.”11,12
The emerging technology of EDOF IOLs has the potential to greatly expand the use of presbyopia-correcting lenses. Dr. Garg concluded his presentation by recommending matching patient goals—and reasonable expectations—to the technology, which may mean using a different lens technology in each eye.
Published:5 February 2019