By Scott K. Schultz, MD
The first published study on the CyPass supraciliary Micro-Stent shows it effectively lowered IOP, precluding the need for more invasive glaucoma surgery in more than 80% of open-angle glaucoma patients.
I think the most interesting thing to note is that these patients failed medical treatment for primary open-angle glaucoma and were otherwise candidates for an invasive glaucoma surgery. However, 1 year after the Cypass stent was implanted, 83% did not need a further glaucoma surgery! That is actually very promising in my view.
Additionally, 2 of the 11 patients who needed more surgery got an additional CyPass stent, and that did the trick. Perhaps placing a second stent when the first is inadequate could further delay more invasive surgery, such as trabeculectomy. Of course, more study is required to make this determination.
Cypass is a conjunctiva-sparing intervention that targets the suprachoroidal space rather than the trabecular meshwork outflow pathway. It’s placed into the supraciliary space through a clear corneal incision, avoiding the formation of a filtering bleb.
This was a multicenter, single-arm study including 65 patients (65 eyes) with uncontrolled medicated IOP > 21 mmHg. At 1 year, the mean IOP reduced to 16.4 mmHg from 24.5 mmHg at baseline, with a mean number of 1.4 medications. The medication load was reduced by an average of 0.8 medications.
The supraciliary micro-stent technique demonstrated a better safety profile than reported for conventional glaucoma surgical interventions, such as tube shunts and trabeculectomy. The most common adverse events included IOP increases > 30 mmHg beyond 1 month (11%, 7/65), transient hyphema (6%, 4/65) and cataract progression (12%, 5/41 phakic eyes).
Unlike the iStent, which can only be inserted at the time of cataract surgery, this study included both phakic and pseudophakic patients. While 5 patients developed cataract that required surgery, so do phakic patients who need retina surgery or any other intraocular surgery for that matter, including trabeculectomy.
It is important to realize that 11% had IOP > 30 mmHg after surgery. It would be helpful to know when this occurred, how long it lasted, what measures were taken and other circumstances about those patients, so we can be better prepared to handle this situation in a tenuous glaucoma patient. This study is limited by being single-arm and prospective in nature. In addition, there was no washout period, but this more accurately reflects real life since a surgeon doesn't stop treatment before glaucoma surgery or make clinical decisions about interventions based on a washout.
I think this technology holds real promise for our patients, and I am looking forward to reading more studies about this device and others like it.