Cutting Edge Glaucoma - Issue 2

40 • CUTTING EDGE - GLAUCOMA alone, compared with the overall implant alone group and the phaco + implant group. These find- ings are consistent with other reports of studies with this device, including the U.S. pivotal trial in refractory glaucoma [23], as well as independent, retrospective [14, 17, 18, 24–26] and prospec- tive [12, 13, 15, 16, 19, 27–29] studies in glaucoma, showing effectiveness at 1 year. Among those, a prospective, open-label study of the implant used alone or in combination with cataract surgery ( N = 149 eyes) [16] showed that the mean medicated IOP and mean number of medications decreased from20.0 (7.1)mmHg and 1.9 (1.3) at baseline to 13.9 (4.3)mmHg ( P <0.01) and 0.5 (0.8) ( P < 0.001) at 1 year, respectively. In our study, the mean percentage change in IOP from medi- cated baseline was 29.3% at month 12, consistent with those published by Mansouri et al . (31% reduction) [16] and Grover et al . (35.6% reduction) [23], for example. Although the patient populations and mode of administration of adjunctive antifibrotic therapy differed in the study by Grover et al . [23], the one by Mansouri et al . [16], and ours, the effectiveness of the gel stent in reducing IOP and need for IOP-lowering medications appear similar. In addition, our results not only demonstrate continued effectiveness of the gelatin implant at 2 years, with a mean % IOP reduction of 27.8%, but also show strikingly stable IOP values from month 1 to 2 years (despite a small, expected elevation at month 3 that may correlate with the median time to first needling). The clinical success rate also remained stable between months 12 (67.6%) and 24 (65.8%), further supporting the long-term effectiveness of the gelatin implant. Overall, 60.7 and 62.7% had IOP ≤ 15 mmHg at 12 and 24 months, respectively. It is also notable that the results were comparable whether implantation was performed as a stand-alone procedure or in combination with cataract surgery. Needling can be an effective intervention in the postoperative management of gelatin stent implantation to restore bleb function, in line with recommendations by the American Academy of Ophthalmology after trabeculectomy [1]. There was variation in needling rate between study sites, as evidenced by the difference between the overall needling rate and the median needling rate. Overall, 41.1% of eyes underwent at least one needling procedure (74.7% [ n = 62/83] occurring within the first 6 months post-surgery), and 44.6% of the needled eyes achieved clinical success criteria at month 24, with comparable results in both treatment groups. The study results are also clinically relevant when compared with other MIGS devices. For instance, in a 2-year pivotal trial, no statistically significant difference in mean IOP reduction from a washed-out baseline was reported at 24 months between patients who received the tra- becular micro-bypass stent during cataract surgery (mean IOP: 18.6 [3.4] mmHg at baseline, 17.1 [2.9] mmHg at 24 months) and those who underwent cataract surgery alone (mean IOP: 17.9 [3.0] mmHg at baseline, 17.8 [3.3] mmHg at 24 months) [30]. Similarly, the mean number of IOP-lowering medications used at 24 months was not statistically significantly different between treatment groups [30], suggesting limited long-term effectiveness of the device. We did not expect to see additional IOP lowering in the phaco + implant group, because many studies looking at trabeculectomy and phaco-trabeculectomy have shown comparable IOP lowering with both pro- cedures [31–38]. Both phacoemulsification and trabeculectomy techniques have evolved, which might explain why more recent papers report no differences in outcomes between trabeculectomy alone vs combined with phacoemulsification. The gelatin stent relies on a similar outflow pathway