Outcomes Of Micro-Bypass Stent Implantation (Istent Inject®) Combined With Phacoemulsification Surgery In Various Glaucoma Subtypes

Istent inject® is used to control intraocular pressure (IOP) in glaucoma patients as a minimally invasive glaucoma surgery (MIGS) device. This study was carried out to assess the efficacy and safety of istent inject® combined with phacoemulsification in a large real word patient cohort. Many studies to date have only assessed the efficacy of istent inject® in patients with mild to moderate primary open angle glaucoma. We set out to assess efficacy and safety of istent inject® in patients with various glaucoma subtypes including primary open angle glaucoma, angle closure glaucomas and secondary open angle glaucomas at various stages of disease severity. 

The use of istent inject® combined with phacoemulsification was analysed in patients over a 6-year period across an NHS Hospital Foundaition Trust Ophthalmology department (01/09/2017 to 01/07/2023). This included patients opearted on across 3 different Hopsital sites within the trust, with all patients opearted under the glaucoma service. 

This retrospective single arm study included 464 patients undergoing istent inject® combined with phacoemulsification, each with a minimum of 12-month post-operative follow-up data. Inclusion criteria was symptomatic cataract in addition to uncontrolled IOP on ≥ 2 IOP lowering agents or contraindication and/or intolerance to IOP lowering medication. Patients all had a diagnosis of ocular hypertension, primary angle closure or a subtype of glaucoma. Patients with a history of previous invasive glaucoma surgery were excluded. Mean and standard deviation were calculated for continuous variables. Pre and post operative mean values were compared using a paired t-test. Calculations were completed using Excel statistical software.

Mean age was 78 years (45-97) and baseline IOP was 18mmHg (8-50). There was a 19.1% mean IOP reduction at 12 months post-surgery, which was maintained at 24 and 36 months (P < 0.001). The mean number of medications was 1.8 post-operatively (at 12, 24 and 36 months) vs 2.5 pre-operatively (P < 0.001). 22% of eyes were medication free post-operatively (at 12 months), 25% (at 24 months), 24% (at 36 months) vs 3% of eyes pre-operatively (P < 0.001). There was a sustained post-operative improvement in BCVA (0.38 pre-op vs 0.19 post-op at 12 months) (P < 0.001). No cases of endophthalmitis or hypotony were reproted. 6% of patients required further glaucoma procedures (selective laser trabeculoplasty, trabeculectomy, presferflo or cyclodiode).

This large, real-world cohort demonstrates a significant and sustained IOP reduction with a marked improvement in medication burden 3 years after iStent inject® and phacoemulsification. An excellent safety profile was displayed with a low rate of further glaucoma surgery required. These findings were demonstrated in a patient cohort including both open and closed angle glaucoma with varying disease severity. This study demonsrates that the utility of iStent inject® in a diverse patient cohort with effective outcomes.