Perspective: Carlos Buznego, MD, on recent Glaukos data
The iStent infinite is under evaluation in an investigational device exemption FDA trial as a MIGS device that is performed independent of cataract surgery.
As we know, the original iStent, the iStent inject (both Glaukos) and the Hydrus (Ivantis) were all approved for implantation in patients with mild to moderate glaucoma in conjunction with cataract surgery. In the current trial, the group of patients was much more difficult to control. These patients had uncontrolled IOP on medications, and many had already undergone failed incisional surgery. It was a tough group with elevated pressures on medications.
The results are impressive, with 76% of patients who received the iStent infinite achieving a 20% reduction in IOP and 50% of patients achieving a 30% reduction in IOP. Obviously, any time we are looking at a new device or product, we need to look at risk vs. benefit. What we see in this trial is what we have seen with prior trials for the iStent products, which is an excellent safety profile. In this trial, no devices were explanted, there were no interventions related to the device, and there were no episodes of hypotony, which can be one of the most devastating effects of any glaucoma surgery.
In addition, the significant pressure reductions seen with this “stand-alone” procedure cannot be attributed to the cataract surgery effect that may confound other studies. This well-controlled study provides further evidence of the efficacy of trabecular bypass. This new indication will allow better options for patients with uncontrolled glaucoma who are not undergoing simultaneous cataract surgery and will fill this important niche in the surgeon’s armamentarium.
In the iDose TR trial, the noninferiority study compares how travoprost with a fast release and travoprost with a slow release perform vs. timolol drops. The results confirmed noninferiority, ie, equivalency. The IOP reductions of 7.9 mm Hg in the fast-release group and 7.4 mm Hg in the slow-release group are comparable to 7.8 mm Hg with timolol. To achieve a 30% reduction in baseline IOP, the groups were nearly identical with 29%, 28% and 30% success. It is interesting that the data separate a little bit if we look at a subgroup of patients who had a 40% reduction in baseline IOP, with 23% in the fast travoprost group, 20% in the slow travoprost group and 13% in the timolol group.
The practical implication for clinicians treating glaucoma is the critical importance of compliance. No matter how well intentioned the physician and patient are, it is difficult to expect someone to use one drop, or a combination of drops, on a regular basis. The concept of a sustained-release medication has been under development for a while, and this is a nice study with results showing excellent IOP control. The adverse events profile is quite good with no incidence of significant endothelial cell loss.
When utilizing topical prostaglandins, there is a significant incidence of hyperemia, which leads to decreased compliance and discontinuance of medications. So, it is interesting to note that travoprost had no evidence of hyperemia in the intraocular version.
In summary, the iDose 2-year data show excellent clinical results and a low incidence of adverse events when compared with the gold standard of timolol drops twice per day. The sustained-release strategy provides patients with a more consistent therapy over the long term. I think it will allow us to bridge the gap between prescribing a medicine and actually having the medication delivered to the target tissue without reliance on the vagaries of patient compliance. An approved intraocular device with sustained-release medication to guarantee consistent levels of therapeutic medication in the eye is a game changer for the doctor and the patient.
Carlos Buznego, MD
OSN Technology Board Member
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