A two-year efficacy trial of the minimally invasive glaucoma surgery (MIGS) iStent Inject W device found it significantly reduced intraocular pressure (IOP) and glaucoma medication burden in adult Japanese open-angle glaucoma (OAG) patients.

Led by Professor Masaru Inatani from the University of Fukui, Japan, in collaboration with Glaukos Japan and Singapore, the multicentre, prospective, post-market surveillance study also demonstrated a high success rate (92% at 24 months) and minimal adverse events.

Commenting on the study, Auckland-based consultant ophthalmologist Dr Aaron Wong said the results are significant as this is not only the largest study on the iStent inject W in Asian eyes but also incorporates two years of follow-up data. “The high proportion of normal tension glaucoma (IOP ≤21mmHg) in Japanese cohorts makes this study particularly relevant to our often difficult to manage NTG patients.”

Around half the eyes (46.3%) in the study had a diagnosis of normal tension glaucoma (NTG), while 81.8% had a mean IOP prior to surgery (on medication) of ≤18mmHg. But at two years, 88% of NTG eyes met the American Academy of Ophthalmology criteria for MIGS success, said Dr Wong, who specialises in glaucoma surgery and MIGS. “Reassuringly the rates of adverse events were low; only two patients (2%) required further glaucoma surgery during the study period.”

This latest industry-funded study corroborates findings from a previous meta-analysis of iStent devices in NTG eyes, showing a reduction in IOP of just over 2mmHg at 12 months as well as a reduction in glaucoma medications of between one and two, he said. “Being able to safely reduce drop burden and lower IOP with this procedure is impactful to a patient's quality of life. As of 2025, a newer generation iStent infinite is available with three stents, compared with the Inject W's two. It will be exciting to see how these ongoing device improvements will affect the efficacy of MIGS procedures for our patients.”