Combining procedures

Combining multiple procedures that reduce intraocular pressure (IOP) in patients with primary open-angle glaucoma (POAG) may be more beneficial than relying on one procedure alone. However, determining if a second procedure will further reduce IOP, or reduce it too much, can be difficult. A clear understanding of the mechanisms of action, potential benefits and increased risks of combining glaucoma procedures, and how a specific combination addresses individual patient needs, are essential for success, say glaucoma researchers. The classic IOP-lowering combined procedure involves adding trabeculectomy to phacoemulsification and intraocular lens implantation for patients with both cataracts and POAG. Phaco alone has been shown to reduce IOP, and trabeculectomy significantly increases the effect, reported Richard A Lewis MD, Sacramento, California, USA, at the 2016 American Academy of Ophthalmology Annual Meeting in Chicago. However, Dr Lewis no longer does combined phaco-trabeculectomy because the procedure is lengthy and more likely to involve complications than separating the two, and trabeculectomy often compromises the excellent visual acuity anticipated after phaco. He also does not consider combining two glaucoma procedures, such as a shunt plus endocyclophotocoagulation, as viable combinations because it is impossible to tell if one or the other is working unless they are done separately. Dr Lewis’s first choice in combined procedures today is phaco plus iStent® (Glaukos) or one of the other new minimally invasive glaucoma surgery (MIGS) options. These procedures are safer and less likely to compromise postoperative vision than phaco-trabeculectomy, and are more effective than phaco alone, he said. Dr Lewis noted that a three-year follow-up of 62 eyes in 43 patients receiving phaco plus iStent showed a mean IOP reduction of 8.4mmHg, or 36%, from pre-op medicated mean IOP, with 79% at less than 16mmHg. Glaucoma medications were also reduced by a mean of 1.7, and 74% of eyes were medication free, with a low incidence of complications (Neuhann T. JCRS 2015). Similarly, FDA Phase III trial data for the CyPass® (Alcon) with phaco saw unmedicated mean diurnal IOP reduced 7.4mmHg compared with 5.4mmHg for phaco alone at 24 months, a 38% additional reduction with CyPass (p<0.001). Only 15% of CyPass eyes required medication compared with 41% of controls. Complications were low, with small increases in hyphaema and hypotony seen in CyPass-phaco eyes, though incidence was less than 3%. “These are minor compared with the IOP reduction benefit,” Dr Lewis said. Richard K Parrish II MD, of the Bascom Palmer Eye Institute, University of Miami, USA, also cautioned against combining glaucoma procedures without a thorough understanding of the effects. Some combinations just don’t make much sense, he said. For example, a trabeculectomy or tube shunt typically have much more IOP-lowering effect than an iStent or CyPass, so it probably is not helpful to add a MIGS device to a successful filtration procedure, Dr Parrish said. Combining a tube or trabeculectomy with a cyclodestructive procedure is risky, because it may reduce IOP too much by both increasing aqueous outflow and reducing inflow. Dr Parrish also questioned combining stents with cyclodestruction. “If substantial IOP-lowering is the goal, then consider that a successful translimbal filtration or trabeculectomy will likely outperform the combination of any other two procedures,” he said. Both Dr Lewis and Dr Parrish emphasised matching IOP-lowering procedures to patient needs, and considering both short- and long-term benefits and risks. “Perhaps we should avoid the term ‘combo procedure’ and think of it in terms of doing what is right for the patient,” Dr Lewis added. Dr Parrish noted that regulators may ultimately define combined procedures, at least as far as reimbursement goes. He noted that CyPass is only indicated in combination with phacoemulsification surgery under its recent FDA approval, and expects that future MIGS device approvals may carry similar limitations. Richard A Lewis: 
rlewiseyemd@yahoo.com Richard K Parrish II: 
rparrish@med.miami.edu

Tags: glaucoma