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Materials, lumen and biocompatibility of a minimally invasive collagen stent for treating glaucoma

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Session Details

Session Title: Presented Poster Session: Glaucoma

Session Date/Time: Monday 07/09/2015 | 09:30-11:00

Paper Time: 10:00

Venue: Poster Village: Pod 4

First Author: : S.Lim UK

Co Author(s): :    R. Lewis   A. Sheybani           

Abstract Details


The development of a novel, permanent and minimally invasive ab interno collagen implant to optimize aqueous drainage to the subconjunctival space. The technology was invented by Dao Yi Yu, M.D. at the Lions Eye Institute, and the product was commercially launched in Europe in 2014. Three different lumen sizes (140, 63, 45 um) have been created and, other than the lumen, all have the same materials and surgical procedure.


The study was conducted in laboratory and in human feasibility in over 12 countries at both hospital and private practice settings. All human patients were conducted under Ethics Committee approved protocols.


Safe placement ab interno-through-sclera requires a flexible yet firm material that maintains shape without disrupting tissue planes. A cross-linked collagen gelatin that is hard when dry but soft when hydrated was tested. Using a bending angle value as a reference, several tests were performed to compare bending forces between the gelatin stent and the most common material used to drain aqueous humor (silicone). Preclinical and clinical testing was also used to determine the optimal lumen size, diameter, tube rigidity, and flexibility and of the stent. 3 different lumen sizes (140, 63, 45 um) were implanted into 294 human eyes.


Accelerated flow testing showed no changes in implant lumen through 10 years. Animal data at 6 years confirm that the implant remains stable. A constant flow rate test was done with varying flow rates. The 6mm, 45 um implant gives a flow of 0.02µl/sec or 1.2µl/min, (at 5 mmHg pressure gradient), providing 6-8 mmHg flow resistance, essentially eliminating hypotony. In human eyes, the 140 um model (n=105) showed a 33% IOP reduction from baseline, compared to a 27% (n=84) and a 40% (n=105) reduction with the 63 and 45 um models, respectively.


Sub-conjunctival drainage of aqueous fluid has been a cornerstone of glaucoma surgery for over a century. The ab interno placement of the gel stent offers a unique alternative for lowering intraocular pressure with a minimally invasive procedure, minimal conjunctival tissue disruption, restricted flow to avoid hypotony, and long term safety.

Financial Interest:

One of the authors gains financially from product or procedure presented, One of the authors travel has been funded, fully or partially, by a competing company, One of the authors receives non-monetary benefits from a competing company., One of the authors receives consulting fees, retainer, or contract payments from a competing company

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