EyeWorld Asia-Pacific June 2011 Issue

38 EW GLAUCOMA June 2011 Moving beyond the ‘gold standard’ for glaucoma by Rich Daly EyeWorld Contributing Editor Alternatives to trabeculectomy may better suit specific patients and clinical goals than that long-dominant procedure A s growing numbers of new devices and surgical procedures for treating various forms of glaucoma continue to emerge, surgeons are increasingly favoring alternatives to the long-dominant trabeculectomy procedure. Although not all of the newer approaches have received FDA approval, both approved and as- yet unapproved approaches may better serve specific patients and individual clinical goals than trabeculectomy, according to some surgeons. These emerging technologies and approaches “will give us a greater ability to individualize instead of using a single gold standard”, said Douglas J. Rhee, MD, assistant professor, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Mass., USA. “There is not one single procedure out there that is going to supplant trabeculectomy for all of the scenarios in which one might find himself; however, there are many clinical scenarios where some of these new procedures are the same or superior to trabeculectomy. We’re moving away from the gold standard concept.” Richard A. Lewis, MD, Sacramento, Calif., USA, also sees the glaucoma surgery field broadening beyond trabeculectomy. “Instead of essentially one hammer [i.e., trabeculectomy] for almost everything, we are beginning to customize the treatment and, more importantly, now have procedures that have or will have fewer complications,” Dr. Lewis said. Among the newer approaches that have received FDA approval and yield better clinical outcomes for some patients is the ab interno Trabectome (Neomedix, Tustin, Calif., USA). The thermal cautery device, which ablates the trabecular meshwork and Schlemm’s canal for about 3-5 clock hours through a temporal clear corneal incision, may best suit patients also undergoing cataract surgery. Dr. Rhee noted that repeated studies have shown that Trabectome treatments provided in conjunction with cataract surgery are about as effective as cataracts done in conjunction with trabeculectomy, although neither approach is as effective as trabeculectomy performed alone. The Trabectome combined surgical approach has the advantage of generally fewer complications than trabeculectomy. The Trabectome combined approach, Dr. Rhee said, best fits open-angle glaucoma patients who need modest pressure lowering, as well as patients who do not need pressure lowering but want to minimize the risk of a post-cataract IOP spike. The use of the Trabectome approach also allows surgeons to perform a subsequent trabeculectomy if the initial device fails, Dr. Rhee and his associates found in a soon-to-be-published study. “Nothing is risk free, but the Trabectome has a relatively low complication rate,” Dr. Rhee said. “The selection of patients is a little more limited because of the limited effectiveness profile.” Such ab interno approaches “are very exciting,” Dr. Lewis said. “They are less traumatic to the eye—and conjunctiva—safer, and faster.” Another surgical option that may benefit some patients better than trabeculectomy is the iStent (Glaukos, Laguna Hills, Calif., USA). Although this snorkel-like device had not yet received FDA approval as of late December, research indicates that it provides better IOP control when combined with cataract surgery than trabeculectomy combined with cataract removal, as well as lower complication rates, Dr. Rhee noted. The iStent “offers a very safe clear corneal approach to placement of a tiny transtrabecular stent,” said Louis B. Cantor, MD, chairman and professor of ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, Ind., USA. “If this device is able to achieve good IOP reduction, it offers an advantage over many of our more invasive or complex procedures.” Standalone option Alternatively, early stage or mild open-angle glaucoma patients who do not need cataract surgery and don’t want a trabeculectomy may benefit from canaloplasty, said Dr. Rhee. The procedure also suits patients whose glaucoma has advanced to the point where the physician is concerned that dynamic anterior chamber changes during a trabeculectomy procedure (repeated flattening and refilling of the anterior chamber) could endanger the optic nerve. Dr. Cantor noted that a canaloplasty is “technically challenging” but is effective in enhancing the trabecular outflow while avoiding the creation of a filtering bleb on the eye. “I believe that the next generation of glaucoma surgery should strive to control IOP without creating a bleb, as bleb- associated complications are the Achilles’ heel of standard glaucoma filtering surgery today.” The external approach of canaloplasty uses a dissection down to Schlemm’s canal, where a catheter is threaded through. The procedure aims to leave a dilated canal, left under tension by a 10-0 prolene suture, along with an internal scleral lake that functions as an internal bleb. Although no head-to-head comparisons have been conducted between canaloplasty and the Trabectome, Dr. Rhee noted that canaloplasty’s “success profile” is superior to that reported for the Trabectome. Research indicates that a failed canaloplasty would reduce the ability to perform a subsequent trabeculectomy, Dr. Rhee said. Subsequent surgical treatment with a tube device is recommended. “Canaloplasty and the Trabectome procedure are mutually exclusive,” Dr. Rhee said. “Once you do one, you cannot do the other.” However, effective trabeculectomies are still possible in the cases of failed Trabectomes and iStents. Patients with refractory glaucoma also have the option of an endolaser cyclophotocoagulation procedure. Additionally, Dr. Rhee noted the endolaser camera can provide “significant help” when performing other procedures. The device generally has the same risks and patient profile as the Trabectome.