Eyeworld

JUL 2012

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

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26 EW CATARACT July 2012 OVDs: Benefits of cohesives, dispersives, or both by Michelle Dalton EyeWorld Contributing Editor utes and adds more dispersive OVD to further protect the endothelium when performing segment removal." But prior to implanting the lens, he prefers a cohesive OVD that will "come out easily when you're aspi- rating at the conclusion," he said. The best pearl Dr. Hovanesian can offer? "Keep the lens and the pieces in the bag, posterior to the cornea as much as possible," he said. "You want to protect the cornea from fragments." Beyond the usual Dr. Assil said he's starting to perform "a lot" of intraoperative aberrome- try, especially on his premium IOL patients, and "I really need all the OVD out of the eye to take the pseudophakic measurements," he said. "I need to rely on a cohesive that will come out when I need it to." OVDs left in the eye can result in pupillary block, he said, and pres- sure can spike into the 40s and 50s. In cases with unhealthy or com- Source: Getty Images The type of OVD used is based upon where you are in the surgery W hen it comes to ophthalmic viscosur- gical devices (OVDs), understanding their individual properties can help surgeons choose from the multitude of options currently avail- able. What used to be simply either high viscosity cohesives or low vis- cosity dispersives has mutated into subclasses as newer products have both cohesion and dispersion prop- erties, and some products have vials of both a cohesive and dispersive. Highly viscous OVDs tend to provide better anterior chamber depth and stability, said John A. Hovanesian, M.D., clinical instruc- tor, Jules Stein Eye Institute, Los Angeles. "Cohesives are good for their clarity," he said. "There's less tendency for pressure spikes because we can generally remove all the ma- terial during surgery." Conversely, dispersives coat better and provide greater endothelial protection as they are better at remaining in the eye during high flow rates, but are more difficult to remove. The lower viscosity dispersive can help "parti- tion" spaces that may be necessary in complicated phaco, he added. The third category, viscoadap- tives, behave like a dispersive in that they break apart when flow increases, but are viscous and cohesive under lower turbulence. For Kerry K. Assil, M.D., med- ical director and chief executive offi- cer, Assil Eye Institute, Beverly Hills, Calif., "cohesives comprise 95% of my universe," he said, noting he uses Healon (Abbott Medical Optics, AMO, Santa Ana, Calif.) in uncom- plicated surgeries and Healon GV (AMO) on eyes with short axial length and during phakic IOL implantation; he dubs it "the Poppa Bear of viscosity." Barry A. Schechter, M.D., direc- tor of cornea and external disease, Florida Eye Microsurgical Institute Inc., Boynton Beach, said he's cau- tious with Healon "because you're going to have the possibility of a post-operative pressure spike as it doesn't come out of the eye as freely as some other OVDs might." In patients with a dense lens, Dr. Schechter uses a combination of OVDs because he "often redistrib- promised corneas, Dr. Hovanesian opts for dispersives over cohesives. Generally speaking, however, he uses AmVisc (Bausch + Lomb, Rochester, N.Y.) and STAARVISC (STAAR Surgical, Monrovia, Calif.), but "I've used others with equal success." "Healon V holds the space open nicely; if you've got a mature cataract and you're concerned about posterior pressure or lens proteins leaking forward from the capsulo- tomy, you might get a better result with a higher density cohesive OVD," he said. Also, if surgeons use the soft-shell technique they'll need to displace the dispersive into the chamber with a layer of cohesive OVD behind it, he said. A similar argument can be made for eyes with broken zonules or Fuchs' endothelial dystrophy. "But you're talking about two vials, and that adds to the expense of the surgery by about $25-40," he said. It was precisely the cost issue that led Dr. Schechter to consider using Viscoat (Alcon, Fort Worth, Texas) as a method to close the wounds. "Sutures cost $30, and we were challenged to find more cost-effec- tive methods to close my cataract in- cisions," he said. Since he was using DuoVisc (Alcon), he tried using "just a little bit of Viscoat that remains; I enter through the counter incision, with the cannula bent 90 degrees to apply the OVD in a thin line directly to the internal lip of the main cataract incision. This spackles the wound closed." In a 50-patient case series he presented at this year's ASCRS•ASOA Symposium & Congress comparing Viscoat to stromal irrigation for cataract wound closure, Dr. Schechter reported no pressure spikes were noted in either group, and post-op, the eyes with the OVD were quieter than the ones with saline stromal irrigation. Dr. Assil said the technique "could give a better closure," but he prefers to concentrate on ensuring excellent wound architecture. "You'll know if you have a tight enough closure," Dr. Assil said. "Personally, if I was moving away from sutures, I'd probably use a biologic tissue glue as a sealant." Although dispersive OVDs have the stickiness needed, "I'm not 100% they will provide a meaning- ful seal," he said, but "it's an inter- esting idea," and he thinks using readily available materials to seal a wound holds value. "I'm a little concerned about putting anything that occupies vol- ume in between the two edges of the wound if it might slow down wound healing closure rather than hasten it," Dr. Hovanesian said. In Dr. Schechter's study, no wound leaks were noted at the first post-op exam (2 hours) or at day 1 post-op or later, he said, but he also acknowledged that further studies are warranted. "Our biggest goal is to be atrau- matic with surgery by not using ex- cess fluid, minimizing phaco energy, and getting out as quickly as possi- ble," Dr. Hovanesian said. EW Editors' note: Dr. Assil has financial interests with AMO. Dr. Hovanesian has financial interests with AMO and Bausch + Lomb. Dr. Schechter has financial interests with ISTA Pharmaceuticals (Irvine, Calif.) and Bausch + Lomb. Contact information Assil: 310-651-2300, info@assileye.com Hovanesian: 949-951-2020, jhovanesian@harvardeye.com Schechter: 561-737-5500, bdsch77@aol.com

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