EyeWorld Asia-Pacific June 2014 Issue

37 EWAP CAtArACt/IOL Pseudophakic dysphotopsia June 2014 by Ellen Stodola EyeWorld Staff Writer Managing multifocal IOL dysphotopsia Dysphotopsias can be a potential problem after surgery, especially with multifocal IOLs O ne 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, Pa., U.S.; John Berdahl, MD , Vance Thompson Vision, Sioux Falls, SD, U.S.; Audrey Talley Rostov, MD , cornea, cataract, and refractive surgeon and partner, Northwest Eye Surgeons, Seattle, Wash., U.S.; and Douglas Katsev, MD , Sansum Clinic, Santa Barbara, Calif., U.S., 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 AT A GLANCE • Dysphotopsias can occur with all types of IOLs but may be more common with multifocals. • Many adapt to dysphotopsias, but in severe cases, a lens exchange may need to be performed. • Choosing the right candidate for a multifocal at the onset is important. 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 light rays hitting the square edge of the optic. Source: Douglas Katsev, MD continued on page 39