AUG 2013

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

Issue link: https://digital.eyeworld.org/i/153099

Contents of this Issue


Page 44 of 66

42 EW GLAUCOMA August 2013 February 2011 Glaucoma editor's corner of the world First-line selective laser trabeculoplasty: Has its time arrived? by Tony Realini, MD L aser trabeculoplasty has been a key component of glaucoma therapy for decades. There has been an ongoing discussion about where laser treatment fits into the glaucoma therapy paradigm. In this issue's "Glaucoma corner of the world," Tony Realini, MD, reports on a debate between Jay Katz, MD, and Remo Susanna Jr., MD, on when to recommend laser treatment. Dr. Katz spoke in favor of early laser treatment, and Dr. Susanna favored waiting until medical therapy has failed. Their discussion is very enlightening. Many studies—including an NEI trial—have shown that laser treatment has equal efficacy to either a prostaglandin or a beta blocker. Despite this, most doctors continue to favor medical treatment as first-line therapy even though the risks are greater for side effects, and there are problems with compliance and increased cost. This has puzzled me. But when I have suggested laser to patients as the first step in therapy, they often have a fear-based response as if the recommendation for a high-tech intervention means their glaucoma is more serious than if I had recommended taking an eye drop. The growing popularity of selective laser trabeculoplasty (SLT) has led more ophthalmologists to recommend laser earlier and even as primary therapy. This is changing the dialogue with patients and is increasing the acceptance of a laser-first approach. Many studies of compliance have shown that patients too often don't fill prescriptions, don't take their drops, have trouble getting drops into the eye, and fail to keep follow-up appointments. The bleak data on compliance is another reason that ophthalmologists are more likely to recommend laser earlier. The concern about ocular surface side effects of topical glaucoma therapy also has contributed to the appeal of laser over topical therapy. The increasing popularity of MIGS angle procedures has favored the use of SLT over argon or diode-based lasers. These lasers cause thermal damage to the meshwork and may interfere with the efficacy of trabecular bypass procedures. The SLT procedure, however, does minimal structural damage to the meshwork and may be more compatible with trabecular bypass implants. Reay Brown, MD, glaucoma editor S ince its commercialization in 2001, selective laser trabeculoplasty (SLT) has reignited interest in laser therapy for glaucoma. Once reserved as a last-ditch effort to keep patients on maximal medical therapy out of the operating room, trabeculoplasty has slowly but steadily made its way down the treatment ladder toward the first step. This trend has been driven by a series of studies demonstrating its efficacy and safety in lowering intraocular pressure (IOP). Yet despite solid clinical and scientific evidence supporting its utility in glaucoma management, few clinicians offer SLT to patients as first-line therapy. At the 5th World Glaucoma Congress in Vancouver, British Columbia, a pair of experts debated the pros and cons of first-line SLT for glaucoma patients. One major advantage of SLT is that it targets the relevant tissue bed, which is the trabecular meshwork. L. Jay Katz, MD, Philadelphia, pointed out, "None of the drugs that we use routinely today work at the site of trabecular outflow. SLT works by rejuvenating trabecular meshwork tissue that is dysfunctional, restoring outflow and lowering IOP." In clinical trials comparing SLT versus monotherapy with a prostaglandin analogue, "one-year results demonstrate that the IOP reduction is remarkably similar between the two," he said, with average IOP reductions on the order of 7 mm Hg with either treatment. The procedure is generally safe, with few side effects, most of which are self limited and resolve without treatment. These include mild inflammation, post-laser IOP spikes (which are largely prevented through the prophylactic use of brimonidine or other fast-acting agents), and rarer issues like transient corneal edema. "In contrast," Dr. Katz said, "the side effects of medications are much more extensive than those of SLT. Further, medications have systemic side effects, a safety issue that is not associated with SLT therapy." Overall, he said, the safety advantage goes to SLT over medical therapy. Efficacy and safety are the major tangible attributes by which IOPlowering therapies are assessed. In recent years, there have arisen sev- eral intangible issues that are also relevant to glaucoma therapies. One of these is adherence. "Perhaps half of our patients are reasonably adherent to medical therapy. In contrast, adherence with SLT is 100%," Dr. Katz said. Another is preservative exposure. Benzalkonium chloride is a ubiquitous preservative in ophthalmic drug formulations. It has also been implicated in ocular surface inflammation, conjunctival and corneal epithelial cell dysfunction, and possibly even reduced success of subsequent filtration surgery, Dr. Katz said. Primary SLT therapy eliminates exposure of the ocular surface to excipient ingredients such as preservatives, he added. Additionally, there are concerns that some of the medications may unfavorably alter ocular hemodynamics and perfusion to the optic nerve, potentially promoting optic nerve damage. This concern, too, is not relevant with SLT therapy, he said. Finally, there is cost. "Several cost modeling analyses in various nations with differing healthcare financing strategies have consistently shown that SLT is cost effective compared to medical therapy with a prostaglandin," Dr. Katz said, "and this difference is increased when medication nonadherence is taken into account." "When considering primary therapy with either a prostaglandin analogue or SLT," he concluded, "equivalent efficacy, better safety, perfect compliance, and cost-effectiveness all favor a change in our treatment paradigm placing SLT as first-line therapy." Remo Susanna Jr., MD, Sao Paulo, Brazil, pointed out that despite these apparent attributes, SLT is not widely used as first-line therapy. "Surveys of both the American Glaucoma Society and Latin American glaucoma specialists show that very few clinicians offer SLT to their patients as first-line therapy," he said. Furthermore, he said, the relative safety issues of SLT versus medical therapy are significant. "We are comparing the potential complications of an irreversible surgical procedure to the once-a-day instillation of an eye drop that can be easily discontinued if adverse events occur," he said. In addition to 20% of nonresponders, the complications that may occur, the unsuccessful rate in five years up to 50%, and the time involved in the procedure, there is the need to check IOP after one to three hours due to the possibility of a spike. On that event, the elevated IOP must be treated and the patient should be seen the next day. Furthermore, after laser trabeculoplasty, medications are still necessary to control and maintain eye pressure in many patients. There are also rare cases requiring trabeculectomy for sustained IOP increases after SLT. SLT has an advantage in patient compliance. However, in a condition that is often asymptomatic, medications may have an important role to play in terms of reminding patients about their condition and the need for vigilance. There is a risk that patients may perceive SLT to be a definitive treatment resulting in complacency with regard to ongoing assessment. "The rule in glaucoma treatment is for us to buy time," he said. "We want to preserve visual function for the patient's lifetime, and we have a limited number of therapeutic options with which to do this." His chief concern is that we do not know for certain whether SLT treatment detrimentally alters the eye's subsequent response to topical medical therapy. "Might SLT reduce the efficacy of medical treatment?" he asked. Until we know for sure, he said, we should save SLT for the time when medical therapy alone is inadequate to control IOP. Dr. Katz disagrees. "Despite having the best selection of medical IOP-lowering therapy ever available, some patients with glaucoma still go blind. Maybe the time for a paradigm shift is now. Maybe first-line SLT's time has come." EW Editors' note: Dr. Katz has financial interests with Lumenis (Yokneam, Israel). Dr. Susanna has financial interests with Alcon (Fort Worth, Texas), Allergan (Irvine, Calif.), and Merck (Whitehouse Station, N.J.). Contact information Katz: ljkatz@willseye.org Susanna: rsusanna@terra.com.br

Articles in this issue

Links on this page

Archives of this issue

view archives of Eyeworld - AUG 2013