Managing multifocal IOL dysphotopsia

Pseudophakic dysphotopsia Managing multifocal IOL dysphotopsia by Ellen Stodola EyeWorld Staff Writer

Patients may complain of an arc image, usually in one quadrant, that bothers them. It is usually described after many of the square-edge optic lenses are placed in the bag. The image is depicted by the drawing of the light rays hitting the square edge of the optic. Source: Doug Katsev, MD Dysphotopsias can be a potential problem after surgery, especially with multifocal IOLs One issue for patients receiving multifocal IOL implants is the potential for dysphotopsias, which can be bothersome and sometimes affect vision. Richard Tipperman, MD, Wills Eye Hospital, Philadelphia; John Berdahl, MD, Vance Thompson Vision, Sioux Falls, S.D.; Audrey Talley Rostov, MD, cornea, cataract, and refractive surgeon and partner, Northwest Eye Surgeons, Seattle; and Douglas Katsev, MD, Sansum Clinic, Santa Barbara, Calif., commented on dysphotopsias and how to address them in multifocal IOL patients. Characterizing dysphotopsias  "One of the things you want to do is characterize them as positive dysphotopsias or negative dysphotopsias," Dr. Berdahl said. "Positive dysphotopsias are things like glare, halos—something that you see. A negative dysphotopsia is more like a shadow, something you're missing that you feel like you should see." He said that negative dysphotopsias can occur with any type of lens, but positive dysphotopsias are more common with multifocal IOLs. Dr. Talley Rostov said that dysphotopsias can occur with both multifocal and monofocal IOLs. "What's more troublesome are the dysphotopsias of the typical glare and halos, especially with the multifocal IOLs," she said. In a small number of patients, these can be so disabling that the physician needs to do a lens exchange. Typically, dysphotopsias from multifocal IOLs are circles or rings around light, Dr. Tipperman said. It is important when evaluating patients to get a clear description of what they are seeing. He said patients oftentimes come in with pictures or drawings to illustrate. "Until you can understand it and categorize it, you can't even begin to treat it," he said. Causes Dr. Katsev said dysphotopsias are light rays that are altered to create an image that falls incorrectly on the retina, and this alteration causes visual complaints in some patients. "They are often caused by the edge of the lens, imperfections in the lens, as well as the diffractive or refractive aspect of the multifocal lens," he said. "As for the premium IOLs, a zonal refractive lens will result in the most complaints, especially early in the recovery process." "Dysphotopsias may be permanent but always soften with time," Dr. Katsev said. "Most often they decrease to a very tolerable level and may even go away." Dr. Berdahl said that when using a multifocal IOL, it's important for the optical system to be pristine. "A multifocal IOL splits light and therefore decreases contrast sensitivity," he said. "Anytime there is a change in a structure at the interface then there's an opportunity for light to be scattered. Multifocal IOLs purposely have changes in them, the rings that are on the IOLs, and when the light hits, it can be scattered, leading to glare or halos. So part of it is the IOL itself," he said. "The second part of it is that light is traveling through a more complex optical system in general." Therefore, if there is some light scatter from an irregular cornea, anterior basement membrane dystrophy, or another condition, this light scatter can reach an intolerable point when paired with a multifocal IOL. "Part of it is choosing the right candidate for a multifocal IOL at the onset," Dr. Talley Rostov said. It's important to ask about the patient's occupation. If the patient will be doing a lot of night driving, he or she might not be the best candidate for a multifocal IOL. It's important to look for uncorrected astigmatism preoperatively as well as any refractive error because they could contribute to dysphotopsias. "The other thing to look for is any dry eye. Make sure that the ocular surface is healthy because the first thing that we get to is the tear layer when we're looking at how light is refracted by the eye, so any ocular surface disease can certainly be problematic for the patient. If there is ocular surface disease, that needs to be adequately treated because it can either change the refraction and/or cause some dysphotopsia," Dr. Talley Rostov said. Counseling patients Dr. Berdahl explains to his patients that multifocal IOLs are the best technology to make them spectacle independent, but he never promises this as a certainty. He explains that multifocal IOLs also have tradeoffs to consider. "One of those tradeoffs is that vision in low light might not be as good," he said. "Another tradeoff is that there's a decent chance that the patient will have rings or halos around some light." If a patient is willing to put up with these possibilities to be more spectacle independent, he or she would probably be a good candidate for this type of lens. Dr. Talley Rostov said it's important to determine if the glare/halo was present immediately postoperatively or occurred gradually. "If it's something that was present immediately postoperatively and hasn't gotten any better, that may be someone who needs an IOL exchange," she said. However, if the patient was seeing great for the first several weeks after surgery, it could be a posterior capsule problem. Different IOL types and designs Sometimes the design of the IOL matters with this problem, Dr. Talley Rostov said. However, she noted that glare and halos can occur with any of the multifocal IOLs. She said there are complaints of waxy or diminished vision, especially a little more with the ReSTOR IOL (Alcon, Fort Worth, Texas). She stressed the importance of paying attention to details with multifocal IOLs. "Multifocal IOLs are especially sensitive to any sort of refractive error, decentration, so it's important to make sure all of those things are spot on." Dr. Katsev said he sometimes finds that both diffractive lenses, the Tecnis Multifocal (Abbott Medical Optics, Santa Ana, Calif.) and the ReSTOR, can have issues, but these can usually be overcome. "Correcting any little refractive error helps to solve the problem," he said. You can't be 100% sure that the dysphotopsias of multifocal lenses won't be a problem, but you can eliminate the patients who might have more of a problem, he said, like those with irregular astigmatism and engineer-type personalities. "When you have an accommodating IOL like the Crystalens [Bausch + Lomb, Rochester, N.Y.], you only need to worry about edge glare and uncorrected refractive error," Dr. Katsev said. Editors' note: Dr. Tipperman has financial interests with Alcon. Dr. Talley Rostov has no financial interests related to her comments. Dr. Berdahl has financial interests with Alcon and Bausch + Lomb. Dr. Katsev has financial interests with Bausch + Lomb, Alcon, Abbott Medical Optics, and Allergan (Irvine, Calif.).