CyPass Micro-Stent® Glaucoma Device
The CyPass Micro-Stent® is a one quarter inch long tube with a collar at one end and holes below the collar. Made of polyimide material, it is intended to be placed in the supraciliary space (next to the uvea).
Aqueous fluid should then be able to flow through this tube, out the small holes, and into the uveoscleral space. It can be implanted alone or at the time of cataract surgery through a very small incision. Although it is manufactured by Transcend Medical in Menlo Park, California, it is still awaiting FDA approval for use in the USA. It is, however, currently available in Canada, the European Union, and elsewhere as an approved device for intraocular pressure (IOP) lowering.
How Well Does the CyPass Micro-Stent® Appear to Work?
One Year Results
Data presented at the 2012 European Society of Cataract and Refractive Surgeons Annual Meeting suggests that the CyPass Micro-Stent® could be a relatively safe and effective treatment of open angle glaucoma. One year after surgery with the CyPass Micro-Stent® alone (without cataract surgery) the IOP was reduced by 26% and glaucoma medication use was reduced by a third in those who had uncontrolled glaucoma prior to surgery. For those whose glaucoma was already under medical control, implantation of the CyPass Micro-Stent® resulted in a 39% average reduction in glaucoma medication use.
When Done at the Time of Cataract Surgery
It is expected that most surgeons will elect to place the CyPass Micro-Stent® in the eye at the time of cataract surgery. However, cataract surgery alone can be expected to lower IOP. And, the higher the IOP prior to surgery the more cataract surgery can be expected to lower the IOP. One study noted that patients with elevated IOP prior to cataract surgery experienced IOP lowering by as much as 8.5mmHg after surgery. That’s pretty impressive.
The recently published “CyCLE” (CyPass Clinical Experience) study evaluated placement of the CyPass Micro-Stent® at the same time as cataract surgery. In those with previously uncontrolled glaucoma, implantation of the CyPass Micro-Stent® at the time of cataract surgery reduced IOP by 35% and medication use was decreased by 49% (on average) one year after surgery. For those whose IOP was already under control prior to surgery, implantation of the CyPass Micro-Stent® at the time of cataract surgery reduced medication use by 75% (on average). Because there was no comparison to cataract surgery alone, however, it is not possible to know whether the IOP and medication lowering effect would have been similar had only cataract surgery been performed.
Two Year Results (with Cataract Surgery)
It appears that the IOP lowering benefit of the CyPass Micro-Stent® combined with cataract surgery may be sustained for years (or at least two, anyway). In those with previously uncontrolled glaucoma, implantation of the CyPass Micro-Stent® at the time of cataract surgery reduced IOP by an average of 37% two years after surgery. On average, only one glaucoma medication was required two years after surgery. Just over one in ten patients had to have additional glaucoma surgery to maintain their target IOP. Again, because there was no comparison to cataract surgery alone it is not possible to know whether the IOP and medication lowering effect would have been similar had only cataract surgery been performed.
Risks of CyPass Micro-Stent® surgery
Based on the few studies available at the time this was written, placement of the CyPass Micro-Stent® during cataract surgery appears to be relatively safe. The main risks appear to be shallowing of the anterior chamber, post-operative IOP elevation, bleeding in the eye (hyphema), and persistent inflammation. No major complications from placement of the CyPass Micro-Stent® have been reported.
The CyPass Micro-Stent® appears to be a relatively safe and effective surgical treatment of open angle glaucoma. It can be placed prior to or after most other glaucoma surgeries. Both fast, relatively safe and effective as well as “minimally invasive” it appears to have great potential as a glaucoma surgical treatment.
As of this writing, the USA FDA Pivotal study is underway. However, as the FDA has requested two year results, we are unlikely to see this device available in the USA prior to 2018. I am hopeful that it will pass the FDA challenge and receive approval for use in the USA. In the meantime it is already being implanted in Canada, Europe, and elsewhere.
For more photos, diagram and information, you may want to see this presentation slide (PDF) shared with us by Mr. Ravi Pamnani, Director of Marketing/Medical Affairs of Transcend Medical, Inc.
- Garcia-Feifoo J, Rau M, Ahmed I, et al. Safety and efficacy of CyPass Micro-Stent as a stand-alone treatment for open-angle glaucoma: worldwide clinical experience. European Society of Cataract and Refractive Surgeons annual meeting, Milan, 8-12 Sept 2012.
- Brown RH, Zhong L, Lynch MG. Lens-based glaucoma surgery: Using cataract surgery to reduce intraocular pressure. J Cataract Refract Surg. 2014;40:1255-1262.
- Poley BJ, Lindstrom RL, Samuelson TW. Long-term effects of phacoemulsification with intraocular lens implantation in mormotensive and ocular hypertensive eyes. J Cataract Refract Surg. 2008;34:735-742.
- Poley BJ, Lindstrom RL, Samuelson TW, Schulze R Jr. Intraocular pressure reduction after phacoemulsification with intraocular lens implantation in glaucomatous and nonglaucomatous eyes; evaluation of a causal relationship between the natural lens and open-angle glaucoma. J Cataract Refract Surg. 2009;35:1946-1955.
- Helmut H, Vold S, Ahmed IK, et al. Initial Clinical Experience With the CyPass Micro-Stent: Safety and Surgical Outcomes of a Novel Supraciliary Microstent. J Glaucoma. 2014 doi: 10.1097/IJG.0000000000000134
- Höh H, Grisanti S, Grisanti S, et a. Klin Monbl Augenheilkd. 2014;231(4):377-81.
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