Real-World Experience Of 2Nd Generation Trabecular Micro-Bypass Stents (Istent Inject): 3-Year Outcomes At A Regional Nhs Ophthalmic Centre In The Uk

Determine 3-year clinical outcomes data regarding effectiveness of iStent inject.

Real-world setting within a standard UK regional NHS ophthalmic centre.

A previously investigated cohort of patients undergoing standalone iStent inject, or combined with cataract surgery, performed between November 2018 and March 2020 was investigated. Baseline data was compared to 3-year outcome data obtained through retrospective notes review. Intra-ocular pressure (IOP), number of IOP-lowering medications, any complications, and any further glaucoma surgery were recorded at least 3 years post-procedure. Data analysis was performed for IOP and number of IOP-lowering medications with paired t-test. Subgroup analysis of eyes requiring further glaucoma surgery compared their baseline Humphrey visual field mean deviations (MD) with those who did not require surgery, using two independent samples t-test.

85 eyes (65 patients) were identified. 45 eyes had 3-year outcome data; 11 patients died, and 27 eyes await review due to Covid-19 backlog (we intend to include in final analysis). Mean baseline IOP was 18.9(±4.5)mmHg, using mean 2.6(±0.8) IOP-lowering medications. By 3-year follow-up, 6 eyes had undergone further glaucoma surgery. Of the remaining 39 eyes, mean IOP was 14.7(±4.0)mmHg, using mean 1.7(±0.9) IOP-lowering medications; both reductions significant (p<0.001) compared to baseline. Complications were cystoid macular oedema (n=1), acutely raised IOP (n=2), and occlusion (n=1 managed by argon iridoplasty). Those requiring further glaucoma surgery had significantly greater baseline visual field loss than those who did not (p<0.001).

The iStent inject is an efficacious and safe treatment option, or adjunct to existing therapies, for glaucoma and ocular hypertension. Our real-world experience has informed our treatment paradigm for the use for iStent inject, being most appropriate for patients with ocular hypertension or early glaucoma. Those in our cohort requiring further glaucoma surgery following iStent inject had significantly more advanced disease at baseline, reflected by visual field loss, than those who did not. Our data demonstrates that, with correct patient selection, sustained efficacy (IOP control and reduced medication burden) of at least 3 years post-procedure may be achieved in a real-world setting.