BackgroundWe report a case with two connected stents ejected simultaneously during an iStentinjectW surgery, a modified second-generation iStent Trabecular Micro-Bypass System.Case presentationA 57-year-old woman with primary open-angle glaucoma underwent a combined cataract and iStentinjectW surgery in her left eye. After the trabecular meshwork/Schlemm’s canal was pierced by the trocar of injector, the delivery button was pressed a first time, but the stent was not ejected. After the button was pressed a second time, connected two stents were ejected. After removing the dislocated stents from the anterior chamber, two stents were implanted into the desired places using another injector. Except for mild hyphema, no postoperative complication occurred. Stereomicroscopic observation showed that the two stents were connected by a broken trocar shaft. An X-ray showed that the trocar shaft was broken at the part referred to as the “sprayed trocar”. Scanning electron microscopy showed that the surface features of the broken trocar and trocar tip represented tensile failure.ConclusionsAlthough rare, considering that the damage was seen at the structurally weak part (i.e., sprayed trocar), the same phenomenon can happen. For patient safety, surgeons are recommended to inspect the device when the deployment of either the first or second stent is unsuccessful during the iStentinjectsurgery.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12886-023-02951-z.