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iStent inject reduces IOP relative to starting pressure
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SAN FRANCISCO — Decrease in IOP attributable to phacoemulsification “maxes out” regardless of starting baseline pressure, whereas the effect of the iStent inject continues to increase with increasing baseline pressure, Inder Paul Singh, MD, told Healio.com/OSN at the American Glaucoma Society annual meeting.
On behalf of the iStent inject pivotal trial team, Singh presented a poster highlighting the 2-year results of the prospective, randomized, controlled trial comparing phacoemulsification alone with phacoemulsification plus iStent inject (Glaukos) that was submitted to the FDA.
Not only was there a statistically significant difference in eyes achieving a 20% decrease in IOP favoring the combination treatment (P = .003), but a significantly greater mean unmedicated diurnal IOP reduction at month 24 vs. baseline also favored the iStent inject group (7 mm Hg vs. 5.4 mm Hg, P < .001).
“[The difference of 1.6 mm Hg] doesn’t seem like a lot, but that’s an average,” Singh said. “Some people may have gotten a 6 mm Hg additional decrease over phaco, and some may have gotten 1 mm Hg. “
In an analysis of baseline IOP and mean unmedicated diurnal IOP reduction, Singh and colleagues found a greater reduction in eyes with higher baseline IOP, which was an expected result. However, they also found that in the phacoemulsification group, regardless of baseline IOP, the pressure decrease hit a ceiling. For eyes at baseline pressure less than 25 mm Hg, between 25 mm Hg and less than 30 mm Hg, and 30 mm Hg and greater, pressure decreases were 5.2 mm Hg, 5.8 mm Hg and 5.4 mm Hg in the control group, respectively. Correspondingly, pressure reductions in the iStent inject group were 6.2 mm Hg, 7.8 mm Hg and 9.8 mm Hg.
“In the phaco group alone, no matter what baseline IOP you started with, you got only a 5-point plus reduction in IOP — the same in every group,” Singh said. This maximum effect of phacoemulsification shows the relative contribution of the iStent in terms of outflow facility, he added.
“No doubt phaco works to bring the pressure down, but it’s not really helping outflow facility. It is changing anatomy, but not actually opening up the outflow,” he said. – by Patricia Nale, ELS
Reference:
Singh IP. Prospective, randomized, multicenter clinical investigation of the Glaukos iStent inject. Presented at: American Glaucoma Society annual meeting; March 14-17, 2019; San Francisco.
Disclosure: Singh reports he is a consultant for Glaukos, Allergan, Alcon, Aerie, New World Medical and Ellex.