Eyeworld

38 | EYEWORLD | DECEMBER 2021 by Ellen Stodola Editorial Co-Director About the physicians Nicole Fram, MD Advanced Vision Care Los Angeles, California Jack Holladay, MD, FACS Clinical Professor Department of Ophthalmology Baylor College of Medicine Houston, Texas Randall Olson, MD Chair Department of Ophthalmology and Visual Sciences John A. Moran Eye Center University of Utah Salt Lake City, Utah miss the lens and the rays that pass through the lens," he said. 1 Nicole Fram, MD, noted that this is a complication that can happen with any type of lens. The patient often has had perfect cataract surgery and is seeing 20/20. However, they may see a dark shadow off to the side temporally. "The first thing you want to do is reassure the patient that you know what it is," she said, adding that it's also important to rule out any retinal or neurological pathology such as a reti- nal tear or detachment. Dr. Fram said Robert Osher, MD, reported that the percentage of patients with negative dysphotopsia on postop day 1 is approximately 15%. 2 The working theory of negative dyspho- topsia based on ray tracing is that some light rays are bent by the lens and some are missed, 3 which creates an illumination gap on the nasal retina causing a dark shadow temporally. In talking to patients before surgery, Dr. Fram said that she mentions that this is some- thing that can occur, particularly in patients needing a high power IOL or who have a large angle kappa. However, she doesn't mention the word "dysphotopsia." Instead, she explains that the intraocular lenses used have the potential to cause glare or shadowing, and if this a problem, she can help. Dr. Fram said it's important to ask if this is- sue is always there or it comes and goes. "If it's not always there or only there in certain light- ing, I'm optimistic that the patient will adapt and not require an intervention," she said. Dr. Osher's research found that 97% of cases resolved within a year. 2 That's very encouraging to the patient, she said. Randall Olson, MD, agreed that this is an issue that's often seen in the first couple of weeks after surgery, though he also sees a lot of patients who have been referred to him with a persistent problem. For the majority of patients, it's not a big issue. However, Dr. Olson stressed that it's im- portant not to tell patients that you don't know COMPLICATED CASES ATARACT C Negative dysphotopsia: How to explain it and management strategies continued on page 40 N egative dysphotopsia is an issue that patients may face following cataract surgery. While it frequently resolves on its own, several physicians said it's important to discuss it with patients and explain what's going on. Jack Holladay, MD, highlighted risk fac- tors that make a patient more likely to develop negative dysphotopsia, though he said you can't definitively predict who will experience the complication. There are risk factors that can predispose it, but it's difficult to predict when it will happen and to whom. Dr. Holladay noted primary risk factors from a paper he wrote, 1 including a smaller photopic pupil, larger positive angle kappa, the shape of the IOL, smaller axial distance of the IOL behind the iris, nasal anterior capsule overlying ante- rior nasal IOL, higher dioptric power if equi-bi- convex or plano-convex, and if the optic-haptic junction of the IOL is not horizontal. Secondary risk factors include the edge design of the IOL (if it's truncated vs. rounded), the material of the IOL, and negative aspheric surfaces. Patients who have a small pupil (around 1.5–2 mm) are at higher risk for experiencing negative dysphotopsia when in bright light, Dr. Holladay said. Dr. Holladay said he tries to stress to physi- cians how important these identifying measures are in helping to recognize high-risk patients preoperatively. Negative dysphotopsia is caused by a gap in rays that pass through the lens that miss the lens. There's not a gap before surgery with the natural crystalline lens, Dr. Holladay said. "There are no rays that make it into the eye that can get between the crystalline lens and the iris," Dr. Holladay explained. "That gap appears as a dark crescent or circle where the rays are missing on the retina. "What we showed in our paper is as you ad- just the lens and make that gap bigger and var- ious things in the eye different, you can make that crescent move more temporally, and you can make the thickness wider or thinner by how much larger that gap is between the rays that

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