Gold
Micro-Shunt for the Reduction of IOP
Gabriel
Simon, M.D., PhD1, Shlomo Melamed, M.D2,
Modi Goldenfeld, M.D.2, Jason M. Clevenger1 M.S.BE
1The Photonics Center, Boston
University. 2Tel Aviv University
Methods
§Clinical study:
Unpaired glaucomatous eyes of 76 patients, ages 18-83, were
implanted with the GMS (mean pre-op IOP = 27.53 mm Hg). Post-operatively, patients received an ocular
examination and IOP measurement using Goldman Applanation Tonometry at 24 hours, 1 week, 2 weeks, 3
weeks, 6 weeks, 3 months, 6 months, 12 months and 18 months. Within one week of surgery, an ultrasound
was performed to verify position of GMS.
Anti-glaucoma medications were discontinued following surgery, and were added at the physician’s
discretion. The study was performed in 2 centers: the Sam Rothberg
Glaucoma Center in Tel Aviv University Medical School, Goldschleger Eye Institute, Israel,( S.M and M.G)
and the Gabriel Simon Ophthalmic Institutes, Barcelona and Madrid, Spain (G.S).
Purpose
To determine the clinical significance and bench flow characteristics of a novel gold
micro-shunt (GMS) in treating increased intra-ocular pressure (IOP) associated with glaucoma. Clinical
results are presented.
The GMS consists of two layers of electroplated gold
containing internal micro-channels to facilitate aqueous outflow. The GMS possesses inlet and egress holes on each end, as
well as fin-like tabs on the posterior end to permit anchoring during
implantation. The device is fabricated
from 99.95%
24K gold, which is both biocompatible and highly resistant to cell growth and adhesion. The overall dimensions of the GMS are 5.21
mm long,
3.2mm wide, and either 45 or 70 µm thick.
GMS possesses 19 internal channels of 24 µm × 50 µm × 2.21mm long ,
which direct flow from the anterior end to the distal (suprachoroidal) end. The
GMS received
CE Mark approval in October, 2005.
GMS Description
Implantation
The GMS is implanted into the supraciliary space to enhance aqueous outflow
between the anterior chamber and the suprachoroidal space. The pressure gradient along the uveoscleral pathway, as discovered by A. Bill,
is utilized as the driving force for flow through the shunt. This pressure gradient is usually between 1-5 mm Hg, and increases with higher
pressures, which
the GMS utilizes to reduce IOP without inducing hypotony.
Results
Clinical Study
§37%
Reduction in IOP at 24 months
§Average
post-op meds were 1.21±0.80 versus pre-op levels of 2.08±0.81
§At
6 months, 64% of patients achieved IOP reduction of 30% or more
*Support for this study was
provided by SOLX, Inc.
Conclusions
The GMS device offers a valuable treatment option for eyes that are
non-responsive to traditional glaucoma therapies. The IOP reduction attained by the GMS
stabilized at 6 weeks, and was ≥30% after 6 months. All eyes tolerated the shunt very well, and
surgical procedure
was easy to perform. The GMS offers a “controlled
cyclodialisis” effect to treat glaucoma, without extended hypotony. Transient hyphema was the most common side-effect, with all cases of hyphema
resolving without
further complication. In bench testing,
the
GMS flow resistance agreed closely with the simulated resistance.
Future Considerations
§Multi-center clinical trial is in
progress to fully explore efficacy of GMS in treating glaucoma.
§Explore the use of Ti-Sapphire
laser in conjunction
with GMS to enable photo-titration.
§Next-generation
GMS will include laser-ablatable windows, to allow adjustment of flow resistance to a specific
patient IOP.
Adverse Events
§One case of shunt extrusion due to
improper
placement, one case of retinal detachment
§Seven cases of transient
hypotony
§Nineteen cases of transient
hyphema, all of which were less than 2 mm