A multifunctional bilayered microstent as glaucoma drainage device.

Commercial non-degradable glaucoma implants are often associated with undesired hypotony, fibrosis, long term failure, and damage of adjacent tissues, which may be overcome by a multifunctional polymeric microstent for suprachoroidal drainage. This study reports the design and fabrication of such devices with tailorable internal diameters (50-300 μm) by solvent-free, continuous hot melt extrusion from blends of poly[(ε-caprolactone)-co-glycolide] and poly(ε-caprolactone) [PCL]. A spatially directed release was supported by bilayered microstents with an internal drug-free PCL layer, and a quantitative description of release kinetics with diclofenac sodium as model drug was provided. Furthermore, the slow degradation pattern (> 1 year) was analyzed and potential effects of 1-5 wt.% drug loading on material properties were excluded. Translational aspects including sterilization by γ-irradiation on dry ice, in vitro biocompatibility, and in vivo implantation were addressed. The promising results support further functional analysis of long-term in vivo performance and suppression of disadvantageous capsule formation.