Gold Micro-Shunt using Photo-Titration for
Additional IOP Reduction
Gabriel Simon1 M.D. PhD., Jason Clevenger2 M.S.BE, Joe Lowery2 M.S.BE MBA
1Boston University Biomedical Engineering, 2Boston University Photonics Center
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§The mass of gold ejected per shot was found to be 5.04 ± 1.41 ng Au.
§Results approximate theoretical ejected mass per shot.
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ICP-ES Results
§The ejected gold per shot is, on average, 83% of the theoretically predicted amount.  This result indicates that a portion of the gold is being melted around the window’s edge, rather than being ablated.
§The theoretical flow resistance allows for treatment of moderate to severe IOP elevation due to glaucoma.  The ability of the ophthalmologist to post-operatively control IOP provides a significant improvement over current shunt technology.
Conclusions
§Additional gold ablation studies will be performed to generate a more complete trend of ejected gold per shot.  In addition, filtration studies will be performed on the solution to determine the size of the resulting Au particulate.
§Bench flow analysis and clinical testing will be performed to determine clinical efficacy of the photo-titratable shunt. 
§The photo-titratable GMS will provide significiant improvement in IOP control over current implantable shunt devices.
Future Implications
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Testing Methods
§The photo-titratable gold micro-shunt was suspended in solution in a test cell and ablated using the 790nm Ti-Sapph laser.
§The shunt is removed from the solution.  The solution is submitted to Inductively-Coupled Plasma Emission Spectrometry (ICP-ES) to determine the quantity of gold ejected from during ablation.
§The solution is evaporated prior to ICP-ES, and the remaining gold is dissolved in an acidic solution.
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Abstract
§A gold micro-shunt has been developed to allow for incremental reduction of flow resistance post-operatively.  The shunt is inserted between the supraciliary space and anterior chamber of in the eyes to promote drainage via the uveoscleral pathway. A 790nm titanium-sapphire laser is used to open additional micro channels to increase uveal scleral outflow and reduce IOP after implantation.  A controlled experiment has been performed to determine the amount of gold ejected from each ablation, and determine the safety of the ablation process. Visualization and photo-titration of the gold micro-shunt is achieved through the anterior chamber. This minimally invasive implantation and photo-titration procedure provides physicians with increased control of IOP reduction in the treatment of open-angle glaucoma. Additional studies are being conducted.
§A photo-titratable shunt greatly increases IOP control by allowing adjustment of flow resistance post-operatively.
§50mJ of energy with a 790nm Ti-Sapph laser effectively ablates 10µm of gold
§Gold implants are generally biocompatible, but excessive gold exposure can result in allergic reactions
Background
1.
Design
§The titratable GMS is designed to be a conduit between the Anterior Chamber (AC) and suprachoroidal space
§The head end of the shunt possesses end-channels, which terminate in 10-µm thick windows.  These windows are designed to be ablated by the Ti-Sapph laser energy.
§This research was supported by SOLX, Inc.
Financial Interest Disclosure