EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/274531
E W GLAUCOMA 76 by Tony Realini, MD, MPH After a prostaglandin, what's next? What is the best adjunct when prostaglandin monotherapy isn't enough? N e arly two decades have passed since the prostaglandin analogues were introduced and rapidly supplanted beta- b lockers as the preferred first-line therapy for IOP reduction in pa- tients with glaucoma. Their advan- tages are clear: superior efficacy, better safety with fewer contraindi- cations, and convenient once-daily dosing for all patients. Less clear is what's next for those patients who require more t han one medication for adequate IOP control. This is a significant pro- portion of all glaucoma patients. In the Ocular Hypertension Treatment Study (OHTS), approximately 40% of patients required two or more medications to achieve a mere 20% IOP reduction. For manifest glau- coma, most clinicians aim for a g reater IOP reduction, typically on the order of 25–35%. Many glau- coma patients will require more than just a prostaglandin to achieve this goal. Our choices include beta-block- ers, adrenergic agonists, topical car- bonic anhydrase inhibitors, or some combination of these three in the form of a fixed combination. Which is best? The case for beta-blockers Beta-blockers may be the second choice for first-line therapy, but they don't seem to be the first choice for second-line therapy. There are important reasons to consider them, said Leslie Jones, MD, Howard University, Washing- ton, D.C. These include cost, con- venient once-daily dosing for many patients, and our familiarity with them given we've been using them for 35 years. However, they don't provide much additional IOP reduction in patients already on a prostaglandin analogue. Additivity of beta-blockers to all three of the prostaglandins has been studied in phase 3 clinical trials, as part of the contributions of elements component of testing the various prostaglandin/beta-blocker fixed combinations. In these studies, the typical additive IOP reduction when timolol was added to any of the prostaglandins was less than 2 mm Hg. The reason for this is unclear. They have complementary mecha- nisms of action, with timolol sup- pressing aqueous formation and p rostaglandins enhancing aqueous outflow primarily through the uveoscleral pathway, Dr. Jones pointed out. Also, beta-blockers do not substantially lower IOP during the nocturnal period, she said. The case for adrenergic agonists The adrenergic agonist brimonidine is often used as an adjunct to prostaglandin therapy. Data support- ing this practice, however, are sparse. "There are a limited number of comparative studies evaluating the additivity of brimonidine or other a gents to prostaglandins," said Lisa Rosenberg, MD, Northwestern Uni- versity, Chicago, "and the results of these studies are variable and con- flicting." In these studies, the average incremental IOP reduction when brimonidine was added to a prostaglandin was approximately 2 mm Hg. "Also, brimonidine does not significantly lower IOP during sleep," she said. The case for carbonic anhydrase inhibitors Topical carbonic anhydrase in- hibitors (CAIs) have been around even longer than prostaglandins. Several studies have evaluated the additivity of carbonic anhydrase inhibitors to prostaglandins. In these studies, adding a CAI to a prostaglandin provides an additional IOP reduction in the range of 2–4 mm Hg. "Overall, these drug have simi- lar mean diurnal efficacy compared with adrenergic agonists and beta- blockers," said Angelo Tanna, MD, Northwestern University. "However, they are generally better tolerated than the other two drug classes, and topical CAIs do lower IOP in both the diurnal and nocturnal periods," he added. "The most common com- plaint with topical CAIs is taste dis- turbance." The case for a fixed combination Regardless of which drug class is used, adding a single agent to a February 2011 February 2014 NE W Our Family of Pre-Loaded CTRs Has Expanded Malyugin/Cionni & Henderson Capsular Tension Rings Now Pre-Loaded in Morcher EyeJets Malyugin/Cionni CTR • Eyelet at curved end is sutured to sclera • Unique design facilitates smooth introduction into capsule • The only injectable Cionni type CTR Henderson CTR • Scalloped design facilitates cortical removal • Maintains the desired stretch of the capsular bag Standard CTRs • Stabilize the capsule during surgery • Available in three sizes to accommodate various capsule bags Henderson CTR TYPE 10C Standard CTRs TYPES 14, 14A, 14C Malyugin/Cionni CTR TYPE 10G 800.932.4202 Visit FCI-Ophthalmics.com to watch the EyeJet informational video. For more information about our Pre-Loaded CTRs, please call us at 800-932-4202 Ex cl usivel y f rom 72-77 Glaucoma_EW February 2014-DL2_Layout 1 1/30/14 10:56 AM Page 76