Long-Term Intraocular Pressure-Lowering and Antifibrotic Effects of a Biodegradable HA-Mg Glaucoma Drainage Implant in a Chronic Glaucoma Rabbit Model.

PURPOSE: The purpose of this study was to evaluate the long-term intraocular pressure (IOP)-lowering efficacy, antifibrotic activity, and outflow patency of a hydroxyapatite-coated degradable magnesium (HA-Mg) glaucoma drainage implant in a chronic glaucoma rabbit model.

METHODS

Chronic glaucoma was induced by anterior chamber injection of a magnetic bead suspension, and glaucomatous damage was confirmed by retinal thinning and optic nerve injury. In a separate cohort, glaucomatous eyes were randomized to trabeculectomy (TL), sham surgery, or HA-Mg implantation (n = 6/group) and followed for 6 months. IOP and corneal diameter were monitored longitudinally, aqueous outflow was evaluated using intracameral trypan blue, and filtration tissues were examined histologically.

RESULTS

Modeled eyes maintained IOP at approximately 30 millimeters of mercury (mm Hg) for 6 weeks, accompanied by retinal thinning and optic nerve damage. After treatment, IOP in the HA-Mg group decreased below 21 mm Hg and remained significantly lower than in the sham and TL groups, in which IOP remained elevated or rebounded. Only HA-Mg-implanted eyes showed recovery of corneal diameter to baseline at 6 months. Trypan blue testing demonstrated persistent subconjunctival drainage in the HA-Mg group, and histology revealed reduced fibroblast proliferation, decreased collagen deposition, and preservation of a clear filtration pathway.

CONCLUSIONS

The degradable HA-Mg implant was well tolerated, provided sustained IOP reduction, and maintained outflow patency while attenuating postoperative fibrosis, supporting its potential for clinical translation in glaucoma filtration surgery.

TRANSLATIONAL RELEVANCE: A biodegradable HA-Mg drainage implant that sustains outflow and limits fibrosis may offer a safer and more durable alternative to permanent subconjunctival drainage devices.