Eyeworld

EW FEATURE 54 Phaco and corneal comorbidities September 2014 • Some pterygium may distort preoperative measurements for cataract surgery, potentially affecting visual outcomes. • Growth of the pterygium, increasing astigmatism, a drop in refraction, and other factors may indicate the need for removal. • Determining when to remove the pterygium may be case dependent. by Maxine Lipner EyeWorld Senior Contributing Writer with-the-rule astigmatism, but when you look at the topography it is asymmetric," she said. "With a nasal pterygium, it will be a lopsided, sideways bowtie with flattening where the pterygium is." Because she is concerned about recurrence, Dr. Jacobs also likes to find evidence of a drop in refraction along with a rise in cylinder associ- ated with pterygium. "If they drop from 20/20 to 20/30 in their current spectacles, and they're taking an extra 0.5 D of cylinder in the axis of the pterygium, that's a sign that it's progressing and becoming visually significant," she said. "If they're fully correctable, I could change the spectacles and wait, but I think that's usually a clue that it's time to go ahead (with removal)." Steven I. Rosenfeld, MD, clinical professor of ophthalmology, Bascom Palmer Eye Institute, Miami, will remove a pterygium in cases of chronic irritation and redness, visual loss or distortion, as well as instances of progressive growth. In cataract cases, there may be more to consider, he finds. "If you're plan- ning to perform cataract surgery and the pterygium is causing induced astigmatism or corneal distortion, that can affect the visual outcome of cataract surgery," Dr. Rosenfeld said. If the corneal topography is distorted or the patient has signifi- cant induced astigmatism from the pterygium, that can affect the accu- racy of the preoperative keratometry measurements and the ability to select the desired IOL power to get the patient seeing clearly or as close to perfect as you would like, he said. The amount of astigmatism to be wary of in cases of pterygium is a grey zone, he said. "If there's asymmetry in the astigmatism and there's moderately more astigmatism in the eye with the pterygium than the other, you could argue that it's worth removing the pterygium be- fore you do the surgery so you have a smooth cornea with a more regular pattern when you do the corneal topography," Dr. Rosenfeld said. Indeed, in rare instances he finds that removal of the pterygium may improve the patient's vision enough that you do not have to rush to do cataract surgery. A bump in the cataract road Stephen C. Kaufman, MD, PhD, professor and vice chairman of ophthalmology, State University of New York, Downstate, likewise finds that the amount of acceptable induced astigmatism varies. "Some patients can have a quarter or a half or even three quarters of a D of astigmatism and it doesn't bother them much," he said, but others complain about this same amount. In such cases, he talks with patients about the risks and benefits and will offer pterygium removal as an option. In addition to visual distur- bance, Dr. Kaufman considers growth of the pterygium. Once a pterygium has encroached onto the AT A GLANCE Handling cases with pterygium A cataract patient with a pterygium growth is in the office. Determining how to best handle this case may be a judgment call. We asked some leading practi- tioners how they contend with such cases. When it comes to pterygi- um removal, Deborah S. Jacobs, MD, assistant clinical professor of ophthalmology, Harvard Medical School, Boston, takes what she terms a "pretty conservative approach," whereby she looks for evidence of progression based on induced astigmatism. Eyeing removal "We don't want to remove it once it's already interfering with best corrected vision because then there may be disruption and even scar tissue in the visual axis," she said. "The clue that it's time to act is when there's increased astigmatism, when the vision drops, and we find that there's usually local flattening (on topography)." After looking at the refraction and the topography, if Dr. Jacobs sees that the pterygium is thickened and inflamed, she is more likely to advise intervention. "If it's small and not distort- ing the vision, I tend to discourage intervention simply if the patient doesn't like the appearance," she said. On topography, the character- istic finding that removal may be needed is a local flattening in the axis of the pterygium. "It would be surface of the cornea more than about 1 mm, if it is actively growing, he recommends removal. "Once the pterygium starts to move toward the visual axis, we're always concerned that after we remove it there can be a residual scar," he said. "If you let the pterygium enlarge too much and encroach onto the visual axis, then the residual scar can cause a permanent reduction in vision that's not possible to correct without more significant corneal surgery." Considering the sequence Dr. Kaufman nearly always recom- mends removing a pterygium 2 to 6 months prior to cataract surgery. He finds that these tend to arise at Once a pterygium starts growing on to the cornea toward the visual axis, it's time for removal. Source: Stephen C. Kaufman, MD, PhD Patient with significant pterygium in her right eye that caused corneal flattening and astigmatism. Source: Steven I. Rosenfeld, MD

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