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Would you recommend multifocal IOLs to patients who have previously undergone refractive surgery?
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EDOF lenses can be used successfully if criteria are met
Before extended depth of focus lenses, I was not using multifocal IOLs in patients who had had prior refractive surgery. I had concerns about quality of vision issues related to any decentration of the multifocal IOL, the potential worsening of vision due to decrease in contrast sensitivity and exacerbating night vision symptoms. I was further apprehensive about the additive loss of visual contrast that could arise from corneal contour irregularities and higher-order aberrations, the presence of irregular astigmatism and/or a decentered/uneven treatment bed. Once the Symfony (Johnson & Johnson Vision) was approved a few years ago, I felt that this implant could be used successfully in post-refractive surgery patients. The central optic is of a larger size, the implant transmits 92% of the light, and the inherent quality of the optic platform provides an enhanced contrast sensitivity as compared with other presbyopia-correcting light splitting technologies. Patient selection, however, is crucial, and we have to look at three requisites: first, if patients were happy and achieved great quality of vision after refractive surgery; second, if their ablation bed is fairly well centered with no or little irregular astigmatism; and third, if they did not experience problems with night vision. If these criteria are met, EDOF lenses can be used successfully. The happiest are post-RK patients who have no more than 8 to 10 cuts and fairly regular astigmatism, as well as post-myopic LASIK patients. In post-hyperopic LASIK patients, I do not use advanced optics if the keratometry reading is greater than 46 D because the negative spherical aberration of the lens combined with a hyperprolate cornea might further diminish quality of vision. It is essential for there to be consistency in overall regularity in the treatment bed of the cornea, with similar magnitude and meridian of astigmatism between the various diagnostic devices.
Patients need to express understanding that their eyes are at a higher risk for postoperative enhancement, and the surgeon needs to be comfortable with management of postoperative surprises, whether it is with refractive laser surgery or IOL exchanges.
Patients who meet the criteria for EDOF lenses are happy patients, in my experience. Their cornea is almost multifocal in nature because of the previous treatment, and this adds up to the depth of focus offered by the IOL. These patients are often able to enjoy a truly enhanced range of vision, from distance all the way through to reading vision, beyond even what naive eyes can experience.
Elizabeth Yeu, MD, is OSN Cornea/External Disease Section Editor. Disclosure: Yeu reports she is a consultant to Johnson & Johnson Vision, Alcon and Zeiss.
Monovision is a better choice
When selecting IOLs for patients who have previously undergone laser refractive surgery, there are a number of things we have to explore. One of them is expectations. These patients have paid out of pocket in order to reduce dependence on spectacles, and what they expect is that lens-based surgery will have the same potential benefits of the laser correction. Yet, we know that even in subjects with no previous surgery, even in the best case series such as in the U.S. trials for multifocal IOLs, acceptance is never 100%, and there are patients who would not choose the same lens again.
There is a long list of reasons that may reduce candidacy to presbyopia-correcting lenses after laser surgery. When we implant multifocal or extended depth of focus lenses, we need to achieve emmetropia, but IOL power is difficult to calculate after laser eye surgery. We have to look for the degree of spherical aberration, coma and angle kappa or chord mu, and sometimes angle alpha. The type of laser ablation, whether myopic, hyperopic or astigmatic, must also be considered when you choose an IOL, and when it was done. Older laser treatments induced more higher-order aberrations than the new generation. Optical zone size in relation to the pupil and other topography findings such as decentered ablations or induced irregular astigmatism need careful evaluation. Patients should be asked to recall if LASIK made it more difficult to drive at night. If this is the case, chances are that multifocal or EDOF lenses will make nighttime difficulties even worse. Lastly, many patients who have had LASIK may have ocular surface disease, also reducing their candidacy for multifocal IOLs.
I do not like to say, “No, you can’t have multifocal IOLs because you had LASIK,” but I tell my patients the many reasons why I think they may not do well. With the understanding that the lens might have to be removed, we can consider using multifocal IOLs, but by and large, I do not advise it. Monovision is probably a much better way to go. Particularly if monovision was already created with LASIK or PRK, and it was successful, we should attempt to match what these patients had before. Even though monovision has its limitations, it does not induce higher-order aberrations nor the visual phenomena that multifocal IOLs induce.
Samuel Masket, MD, is founding partner of Advanced Vision Care and clinical professor of ophthalmology, David Geffen School of Medicine, Jules Stein Eye Institute, UCLA. Disclosure: Masket reports no relevant financial disclosures.