EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78708
30 EW CATARACT June 2012 Trumping endothelial fate by Maxine Lipner Senior EyeWorld Contributing Editor Preserving the endothelium in cataract surgery W hile endothelial cell loss is pretty much an inevitable effect of cataract surgery, ad- vances in technique and technology have helped to opti- mize outcomes, according to Natalie A. Afshari, M.D., associate professor of ophthalmology, Duke University Eye Center, Durham, N.C. The rate of endothelial cell loss these days after phacoemulsification may be as low as 1.2%, study results reported in the January issue of Current Opinion in Ophthalmology show. Recently, with the advent of DSAEK surgery, there has been a lot of attention paid to the corneal en- dothelium. "Instead of the full thickness corneal transplantation, we do partial endothelium because we have better techniques of replac- ing it," Dr. Afshari said. Spurred by this heightened interest, investiga- tors combed the literature to deter- mine how endothelial cell loss is affected by surgical factors as well as the patient's history. Studying endothelial keys One of the keys to sparing the corneal endothelium appears to be the availability of excellent vis- coelastics. "Recent studies are show- ing that there is a reduction in corneal endothelial cell loss after phacoemulsification because we She pointed out that there has been a lot of talk about torsional phaco in which the handpiece deliv- ers side-to-side oscillating ultrasonic movements, which can be helpful in sparing the endothelium. However, she doesn't see this technology as the "holy grail." "The torsional phaco is good but I'd say that any of the newer phaco machines are actu- ally quite good," she said. "By using any of the newer phaco technologies I think that you can minimize the amount of cell loss because you're maximizing your phaco efficiency, and that's really what it's about." Viscoelastic devices can also An eye post-DSAEK. With the advent of the surgery (pictured here), the corneal endothelium has received significant attention Source: Mark Gorovoy, M.D. have better viscoelastic materials and we have modified our surgical technique," Dr. Afshari said. "We are better in preparing and pre-opera- tively knowing how to avoid it as much as possible intraoperatively." Some studies have shown that use of a dispersive viscoelastic that diffuses all over the endothelium is an asset. "The use of dispersive viscoelastic led to reduction of en- dothelial cell loss," Dr. Afshari said. She pointed out, however, that the density of the cataract also plays a role. "The denser the cataract, the more energy that's used and the more possibility that you lose endothelial cells." Some of the patients appear to EyeWorld factoid Once endothelium cells are destroyed by disease or trauma, they are lost forever. If too many endothelial cells are destroyed, corneal edema and blindness occur Source: National Eye Institute be at a higher risk of losing endothe- lial cells. "Some studies show that those patients who have diabetes be- fore the cataract surgery compared to patients who don't are losing more cells," Dr. Afshari said. When it comes to those who have under- gone some form of corneal trans- plant, those who retain their own endothelium with deep anterior lamellar keratoplasty do better after phacoemulsification than those who have had penetrating keratoplasty (PK). "Those patients have their own corneal endothelial cells, and they lose fewer cells during the surgery compared to patients who have had PK before," Dr. Afshari said. "It's interesting that those folks are predisposed to more cell loss." Studies show that any technol- ogy that minimizes the impact on the corneal endothelium can help. "The newer technology, which de- creases the amount of ultrasound delivered on the corneal endothe- lium, decreases the endothelial cell loss," Dr. Afshari said. "The fluid is moving around hitting the corneal endothelium, and there would be less of that if we have less ultra- sound energy on the corneal endothelium." One technique that seemed to spare the corneal endothelium was the phaco chop. "There was a study that looked at phaco chop versus the stop-and-chop, and phaco chop obviously requires lower ultrasound energy so technical modification will help to reduce the loss of corneal endothelial cells," Dr. Afshari said. In the clinic Audrey R. Talley Rostov, M.D., Northwest Eye Surgeons, Seattle, has found that both technique and tech- nology can make a difference here. She prefers a biaxial phacoemulsifi- cation technique, using two small incisions. "I find that works ex- tremely well for minimizing my cell loss," she said. State-of-the-art technology should not be overlooked. "I would say that with the newer phaco ma- chines that allow you to use less en- ergy, less phaco power, the decreased duration and amount of phaco that you use can help preserve corneal endothelial cells," Dr. Talley Rostov said. help with deferring endothelial cell loss. For some patients Dr. Talley Rostov finds a dispersive agent to be preferable. "A dispersive OVD such as Viscoat [Alcon, Fort Worth, Texas] or Duovisc [Alcon], which has a Viscoat-type molecule in it, those are going to coat the endothelium more," she said. "But for the average cataract, do you need to use that? I think the answer is no." Dr. Talley Rostov reserves this for special situa- tions such as cases involving a pa- tient who has undergone a previous corneal transplant or someone with Fuchs' endothelial dystrophy. Vis- coelastic devices can also help with deferring endothelial cell loss. Overall, Dr. Afshari sees the for- tune of the corneal endothelium as dramatically improving. "There was a study in which there was only a 1.2% cell loss after phacoemulsifica- tion," she said. "We have come a long way and we are doing great; the rate has gone way down to nearly insignificant." Because of all of the improvements in technique and technology, practitioners are seeing much less pseudophakic bullous keratopathy. "We have changed the fate of the corneal endothelial cells for the better because of these ad- vances," Dr. Afshari said. EW Editors' note: Dr. Afshari has financial interests with Bausch + Lomb (Rochester, N.Y.). Dr. Talley Rostov has financial interests with Abbott Medical Optics (Santa Ana, Calif.). Contact information Afshari: 919-681-3937, natalie.afshari@duke.edu Talley Rostov: 206-528-6000, ATalley-Rostov@nweyes.com