Eyeworld

APR 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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April 2012 surgery was combined with a trabeculectomy procedure. "When you're doing trabs, you can have an issue post-operatively with the lens moving anterior be- cause of overfiltration," Dr. Friedl said. "The concern would be how much of that is going to affect the overall outcome." Dr. Friedl said she discovered that both anticipated and residual astigmatism numbers were close— within a half or quarter diopter, "which is the same as what's in the literature in standard cases." Dr. Friedl said there were cases in which the lens did flatten or come all the way forward, but the patient still had 20/20 visual acuity with the lens. "It didn't necessarily affect the axis rotation, or if it did, it wasn't enough to throw off the acu- ity," she said. To minimize the potential for more astigmatism, Dr. Friedl said a surgeon should make sure the eye is firm before opening a trab flap or suturing the trab. "Sometimes in a trab we like to close when the eye is softer because you get a little more tightness to your wound, but that can induce more astigmatism, so you would alter your technique that way," she said. Dr. Sarkisian said he takes a conservative approach to combined procedures because of the possibility of inducing astigmatism during filtration surgery. "I typically am not doing com- bined toric and filtration surgery un- less a patient has a large amount of astigmatism in the horizontal axis," he said. "If the patient has 2.5-3 D of astigmatism in the horizontal axis, then I will consider combined surgery." Dr. Sarkisian said he does com- bine the toric procedure with endo- scopic photocoagulation or insert the toric lens during a phacocanalo- plasty or newer minimally invasive glaucoma surgery, such as the iStent Trabecular Micro-Bypass (Glaukos, Laguna Hills, Calif.) or EX-PRESS Glaucoma Filtration Device (Alcon, Fort Worth, Texas). The iStent is awaiting FDA approval. In combined procedures, Dr. Sarkisian offered advice to minimize the chances of surgically induced astigmatism. "Sutures that are too tight are the primary culprit," he said. "Be careful not to tie sutures too tightly close to the cornea. Also, over cau- terization near the limbus can cause surgically induced astigmatism, too." Bleb height also may be a factor, Dr. Sarkisian added. "There's not much you can do about that except wait for the bleb to remodel, and often the astigma- tism diminishes with time," he said. Using a "one punch only" tech- nique with a trabeculectomy to cre- ate a smaller fistula may reduce residual astigmatism, Dr. Sarkisian noted. The smaller fistula reduces out- flow, which means surgeons will not have to tie flap sutures as tightly, he said. Dr. Sarkisian said he also uses a pointy-tipped cautery that uses less energy and allows the surgeon to focus in on active bleeding sites. Dr. Friedl said marking the eye is critical. "If you're doing a combined phaco/trab, make sure you have every axis marked before you make your entry into the anterior cham- ber under the trab flap," she said. "Make sure the eye is nice and full." Toric lenses can be placed in pseudoexfoliation patients, but extra steps must be taken, Dr. Friedl said. "In order to maintain capsular support, you might need to stabilize the capsule with a Mackool hook," she said. A nearly perfect rhexis would be ideal, too. "These patients are more prone to capsular phimosis or the contrac- tion of the capsule if the rhexis is too small," she said. "You want the optic contained in the rhexis, but you don't want it too small that it is increasing the risk of capsular phimosis." EW Editors' note: Drs. Friedl and Sarkisian have no financial interests related to this article. Contact information Friedl: kfreidl@gmail.com Sarkisian: steven-sarkisian@dmie.org

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