Safety and Efficacy of a Membrane-Tube-Type Glaucoma Shunt Device: An Animal Trial

Purpose: To evaluate the safety and efficacy of a membrane-tube-type glaucoma shunt device (MT-device), which was developed to control intraocular pressure (IOP) with a lower chance of complications than conventional glaucoma surgery, in a rabbit model.Materials and Methods: The MT-device consists of an expanded polytetrafluoroethylene membrane (thickness 0.2 mm, area 2.5 x 2.5 mm(2)) and a tube (internal diameter 76 mu m, external diameter 175.5 mu m, length 7 mm) attached to the membrane. The device was implanted into the left eyes of nine New Zealand white rabbits. The tube was placed in the anterior chamber through paracentesis, and the membrane was fixated on the scleral surface; this induces aqueous drainage from the anterior chamber to the subconjunctival space. IOP, filtering bleb morphology, depth and inflammation of the anterior chamber, and possible complications were evaluated periodically for 8 weeks after surgery. Histological sections were analyzed at 2 and 8 weeks after the surgery.Results: Mean IOP decreased from a preoperative value of 8.7 1.2-4.7 +/- 0.6 mmHg at postoperative 8 weeks (p < 0.05). The filtering bleb was maintained during the study period. There were no major postoperative complications. Histologic assessment revealed that 2 weeks after the surgery, fibrous encapsulation, inflammatory cells, and fibroblasts were observed around the MT-device; however, 8 weeks after the surgery, minimal inflammation was observed.Conclusions: The MT-device showed good biocompatibility and effective IOP reduction with a low risk of complications in a rabbit model.