Efficacy and safety of a novel ab interno supraciliary HA-Mg biodegradable glaucoma drainage plate implantation in rabbit eyes

The uveoscleral outflow pathway is one of the important pathways for aqueous humor outflow. Implanting ab interno glaucoma drainage devices through this pathway does not require conjunctival filtering bleb formation, thereby avoiding bleb-related complications. However, permanent drainage devices can easily cause damage to the corneal endothelium. We hypothesize that a novel ab interno supraciliary HA-Mg biodegradable glaucoma drainage plate through the uveoscleral pathway can reduce corneal endothelial cell damage, demonstrate an IOP-lowering effect, and form and maintain a physiological aqueous outflow pathway after complete degradation and absorption. Sixteen New Zealand white rabbits were randomly assigned to three groups: HA-Mg drainage plate group (10 right eyes), trabeculectomy group (6 right eyes), and control group (16 left eyes). Results showed that the intraocular pressure (IOP) in the ab interno plate group was significantly lower than in the other two groups within the first 20 weeks after surgery (P < 0.0001). After 21 weeks, the IOP in the ab interno plate group gradually returned to the levels of the other two groups. Within 5 months after surgery, the plate was completely degraded and absorbed, the aqueous humor drainage pathway extended to the supraciliary space at the anterior chamber angle, and a water sac-like gap formed above the ciliary body. At the 6th month postoperatively, the number of corneal endothelial cells in the ab interno supraciliary HA-Mg drainage plate group was 2446.0 ± 104.3, and in the control group was 2391.67 ± 49.6, revealing no statistically significant difference (t = -1.611, P = 0.168). In summary, the HA-Mg biodegradable glaucoma drainage plate placement in rabbits was well fixed in the supraciliary space. After 5 months of implantation, the internal drainage plate was completely absorbed, and the implantation procedure and degradation process did not cause damage to the corneal endothelial cells. Compared with the trabeculectomy group, the ab interno plate group maintained a significantly lower IOP for a longer period in this normotensive rabbit model. Although an aqueous humor drainage channel was formed after degradation, the IOP gradually returned to the levels of the control group.