Within this paper we analyzed the technical feasi-
bility of a novel microstent for glaucoma therapy. For lower-
ing of intraocular pressure, the flexible polyurethane (PUR)
implant is designed to drain aqueous humour from the anterior
chamber of the eye into subconjunctival, or alternatively
suprachoroidal, space. The microstent includes a biodegrad-
able, flow resisting polymer membrane serving as temporary
flow resistance for the prevention of early postoperative hy-
potony. A biodegradable local drug delivery (LDD)-device was
designed to prevent fibrous encapsulation. Biodegradable com-
ponents were made of flexible, nonwoven membranes of
Poly(4-hydroxybutyrate) (P(4HB)). Polymer samples and
microstent prototypes were manufactured by means of dip coat-
ing, electrospinning and femtosecond-laser micromachining
and characterized in vitro with regard to structural and fluid
mechanical properties, degradation behavior and drug release.
Bending stiffness of PUR-tubing (62.53 ± 7.57 mN mm 2 ) is
comparable to conventional glaucoma drainage devices in a
tube-plate design. Microstent prototypes yield a flow resistance
of 2.4 ± 0.6 mmHg/μl min −1 which is close to the aspired value
corresponding to physiological pressure (15 mmHg) and aque-
ous humour flow (2 μl min −1 ) conditions inside the eye.

• Development of a biodegradable flow resisting polymer membrane for a novel glaucoma microstent