Early to late explantation of Hydrus microstent MIGS device: A case series

The Hydrus microstent was approved by the FDA in August 2018 for use with cataract surgery to reduce IOP in patients with mild to moderate primary open angle glaucoma (POAG). Pivotal clinical trials demonstrated its overall safety and efficacy in lowering IOP. However, malpositioning of the implant can result in uveitis-glaucoma-hyphema (UGH) syndrome necessitating device explantation. Here we report four such cases and their associated challenges. We also highlight the importance of early recognition of post-operative complications for ease of implant removal.

Case 1: A 75-year-old female patient was referred for chronic granulomatous anterior uveitis with cystoid macular edema (CME) and uncontrolled IOP in the left eye after cataract extraction with Hydrus implantation. On gonioscopy, the implant was occluded and embedded in the iris. The patient underwent removal of the Hydrus implant 10 months after the initial surgery with canaloplasty to control IOP.Case 2: A 71-year-old male patient on dual anti-platelet developed intraoperative hyphema during cataract extraction with Hydrus microstent in the right eye. Post-operatively, clopidogrel was stopped, but hyphema persisted with uncontrolled IOP. The Hydrus was noted to be syneched against the iris face. The patient underwent anterior chamber washout with Hydrus explantation and Ahmed glaucoma valve implantation 16 days after the first surgery.Case 3: A 76-year-old patient developed persistent granulomatous anterior uveitis in the left eye after cataract extraction with Hydrus microstent. On gonioscopy, the Hydrus ostium was seen resting on the iris without occlusion, and the patient underwent Hydrus removal with nasal goniotomy 3 months after initial surgery.Case 4: A 63-year-old patient underwent cataract extraction with endoscopic cyclophotocoagulation and a complex Hydrus microstent implantation requiring multiple attempts. Eleven months later, the patient was found to have uveitis-glaucoma-hyphema syndrome and macular edema, and the Hydrus was noted to be insufficiently inserted and posteriorly rotated with contact against the iris. The Hydrus was explanted, and nasal goniotomy was performed.

Hydrus microstents that are malpositioned can result in persistent uveitis-glaucoma-hyphema syndrome. Explantation between 2 weeks and 11 months successfully resolved post-operative uveitis and hyphema, but all cases required additional glaucoma-hyphema syndrome. Early recognition is important since late removal was more challenging due to the implant becoming embedded in the iris.