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EW GLAUCOMA 32 May 2018 Research highlight by Maxine Lipner EyeWorld Senior Contributing Writer medications, we were doing SLT to try and get them off of their medi- cation." Investigators divided the prior glaucoma surgery patients into two groups based on their IOP, placing them into a higher or lower pressure group. For those with the higher pressures, investigators determined that at 1 month there was an 18.1% reduction in IOP, at 6 months 16.7%, and at 1 year 8.4% in this group, Dr. Kammerdiener reported. For those with lower pressures, there were reductions of 2.3% at 1 month, 3.4% at 6 months, and 1.1% at 1 year. Cases in which there was more than a 20% drop in IOP from before the SLT procedure were deemed a success. "In the groups with pri- or glaucoma surgery, 27.9% met success criteria," Dr. Kammerdiener said. Meanwhile, for those who had never undergone glaucoma surgery, 31.7% had a 20% drop at the 1-year mark. Dr. Kammerdiener pegs this as comparable and stressed the significant number of people this could help. Clinical potential SLT can make a big impact in de- laying the need for major glaucoma surgery in this group, Dr. Kammerd- iener thinks. "The higher IOP group is the one that we're trying to keep away from surgery," she said. "It's the group that often general oph- thalmologists start sending back to glaucoma doctors." Glaucoma sur- geries don't last forever, she pointed out. "Even if you buy patients 1 year or 2 by doing the laser, that's less risk they undertake than with surgery, and that much longer they have until they potentially need another procedure." Dr. Sharpe views the results as promising. While the SLT was only able to reduce pressure by 20% in 30% of cases, these outcomes made investigators think that they were offering something that did have a benefit for patients. "We weren't expecting a high success rate their patients to glaucoma special- ists once they began undergoing in- cisional surgery. "At that point, the outflow system is no longer working well," she said. In the South Carolina area where the investigators were practicing, there was an additional issue. "There are limited numbers of glaucoma doctors," Dr. Kammerdie- ner said. "One of the things that we were trying to do was provide some guidance and more information that may particularly help the compre- hensive ophthalmologists, many of whom do SLT." The idea was to see if there was a good reason to use SLT in these patients, which would enable them to take back some of the management of post-incisional surgery patients. As R. Allan Sharpe, MD, ophthalmology resident at MUSC, noted, investigators thought that the patients could possibly benefit from retaining access to SLT after incisional surgery. "We often offer SLT to patients who are in a tough place where they're on all the drops that they can tolerate. A lot of these patients have had major glaucoma surgery before and they're hesitant to undergo a subsequent operation," he said. In such cases, practitioners thought it was buying them time. "Given this kind of practice pattern, we wanted to look back and for- mally evaluate the true effect of the laser in these types of patients," he said. In the study, investigators looked back at specific SLT cases from their MUSC clinic with at least 1 year of follow-up. Included were 53 patients who had prior incision- al glaucoma surgery at least 1 year before undergoing SLT, as well as 53 controls. Such patients were un- dergoing SLT for different reasons. "Many of them were on medical therapy and had elevated IOP, so SLT was done in addition to their medication to try to lower them to target pressure," Dr. Kammerdiener said. "But on some patients, because of non-compliance issues, cost of medication issues, or side effects of SLT have a similar IOP reduction to those who have not had such prior surgery, according to Leah Kam- merdiener, MD, Lowcountry Eye Specialists, Ladson, South Carolina. SLT's promise The idea for the study, which took place during Dr. Kammerdiener's time at the Medical University of South Carolina (MUSC), Charles- ton, South Carolina, grew out of the realization that many general ophthalmologists were referring SLT in post-incisional glaucoma surgery patients J ust because a glaucoma patient has already had a trabeculectomy does not mean that practitioners should forgo later selective laser trabeculoplasty (SLT) if the pressure is not low enough. Study results published in the International Journal of Ophthalmology 1 indicate that those who have had prior inci- sional glaucoma surgery followed by Second glance SLT remains a viable option for those who have undergone prior incisional glaucoma surgery. Source: R. Allan Sharpe, MD

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