A Novel Squid Glaucoma microShunt for Controlled Release of Aqueous Humor

BACKGROUND: Glaucoma is the second leading cause of blindness, affecting 80 million patients globally and 3 million in the US. Elevated intraocular pressure (IOP), caused by blockage of aqueous humor (AH) outflow from the anterior chamber, is an important risk factor. After medical treatments fail to control IOP, a glaucoma drainage device (GDD) is implanted. Current GDDs have major drawbacks: (1) large sizes requiring extensive surgical dissection, (2) uncontrolled AH release risking vision loss, and (3) prolonged inflammation/fibrosis leading to 50% failure rate at 5 years. To address this clinical need, we designed a new GDD, the Squid Glaucoma microShunt (SGS). HYPOTHESIS: We hypothesize the SGS with a unique design based on the human aqueous-episcleral vein model will reduce IOP slowly and reliably, being an effective surgical glaucoma treatment. METHODS: A 3D model of the SGS was rendered using computer-aided-design software SolidWorks. SGS is 90% smaller, designed to release AH in a slow, sprinkle-like fashion. To reduce inflammation, SGS will be coated with patented low-cost ultrananocrystalline diamond (UNCD) film exhibiting superb biocompatibility. A pair of patented micro forceps were designed for easy insertion, promoting 50% reduction in surgery time. An in-silico ANSYS fluidic simulation was designed to study fluid flow and pressure drop. To test the efficacy, UNCD was coated on an Ahmed® Shunt and inserted in a rabbit eye with the control eye having an uncoated shunt. RESULTS: The ANSYS simulation showed that the SGS reduced IOP by 50% from 17 to 9 mmHg. At one year, the rabbit eye with UNCD coated Ahmed® shunt was quiet with low IOP, while the uncoated shunt failed within days due to intense inflammation/scarring. SGS and micro forceps prototypes were fabricated using Stratasys® 3D-printers. Our SGS would make early surgical intervention an option for glaucoma patients with presumably better outcomes, preventing blindness.