Polymeric check valve with an elevated pedestal for precise cracking pressure in a glaucoma drainage device

Area of Science:

• Biomedical Engineering
• Materials Science

Background:

• Glaucoma drainage devices (GDDs) require precise intraocular pressure (IOP) regulation and effective aqueous humor turnover (AHT).
• Existing GDDs may face challenges in achieving predictable cracking pressure and preventing reverse flow.

Purpose of the Study:

• To design, fabricate, and characterize a novel polymeric micro check valve for GDDs.
• To enhance the predictability of cracking pressure and ensure effective aqueous humor drainage.
• To prevent reverse flow in GDDs.

Main Methods:

• Fabrication of a three-layer PDMS micro check valve with a parylene C coating.
• Utilizing a feedback channel to prevent reverse flow.
• COMSOL simulation to optimize valve membrane and parylene C film thicknesses (58 μm and 1 μm, respectively).

Main Results:

• The fabricated GDD exhibited a cracking pressure within the normal IOP range (1.33-2.67 kPa).
• Forward flow rate of 4.3 ± 0.9 μL/min at 2.5 kPa, sufficient for human AHT (2.4 ± 0.6 μL/min).
• No reverse flow observed up to 4 kPa hydrostatic pressure.

Conclusions:

• The developed polymeric micro check valve offers precise IOP control and efficient AHT for glaucoma treatment.
• The design, incorporating a pre-stressed membrane and feedback channel, ensures reliable GDD performance.
• This micro check valve represents a promising advancement in glaucoma therapeutic devices.