David Huton: I’m David Hutton from Ophthalmology Times. The American Academy of Ophthalmology hosts its annual conference in Chicago, and we provide all the coverage you’d expect. Today I am joined by Dr. Mark Packer of Packer Research Associates to discuss his poster titled “Safety and Efficacy of a New FDA-Approved Dispersive Ophthalmic Viscosurgical Device”.
Dr. Packer, thank you very much for being with us today. Tell us about your presentation.
Mark Packer, MD: Thanks David. Well, I’ve worked with Bausch and Lomb for the past decade to develop a new viscoelastic. And we finally brought this to market, it’s called ClearVisc. It’s the brand name and it just got FDA approved, and it’s a viscoelastic dispersive. Its particular objective is therefore the protection of the corneal endothelium in particular, but also of other interocular structures during the process of phacoemulsification.
So, as you may know, the way the FDA approves these things is to do a blinded prospective randomized study in which patients are operated on for routine cataract surgery either with a new experimental device or with a comparator control device. And in this case, we chose the market leading dispersive viscoelastic, VISCOAT, manufactured by Alcon, as a control. And so patients were randomized to surgery with either ClearVisc or VISCOAT.
The unique property of ClearVisc is really that it contains sorbitol. Sorbitol is therefore essentially an antioxidant, and the concept here is to quench the free radicals that are produced during the phacoemulsification process when the ultrasonic tip vibrates in the eye. There are many chemical changes going on, including the production of free radicals, which can then convert to these highly reactive oxygen species that damage the corneal epithelium. So, the inclusion of sorbitol is sort of what makes ClearVisc special.
And so anyway, we did this head-to-head, randomized, masked control trial. Basically, there are two important endpoints. The first is in terms of effectiveness, we look at the protection of the corneal endothelium. And so what we’re looking at here is the density of corneal endothelial cells, both before and after surgery at about three months, which is about when the initial type of damage started. calm. And we’ve kind of reached a steady state, if you look at studies of the corneal endothelium after cataract surgery, you see there’s a drop right away usually about 10% in most studies, and then it sort of slows down to a physiological rate of about 1% to 2% per year thereafter. So we looked at endothelial cell density, efficiency, how we protect the endothelium.
And then, for safety’s sake, we look at the increase in intraocular pressure, because as any surgeon knows, if you leave residual viscoelastic in the eye, you tend to have a pressure spike which is quantified by the FDA by setting a threshold of 30 millimeters of mercury. So pressures below 30, we sort of ignore; if the pressure reaches 30, then we record an adverse event. And then surgeons are allowed to treat either with topical medications or an aqueous tap, whatever they deem necessary. But below 30, they don’t deal. And this is so as not to mask any pressure peaks.
So we recruited 184 eyes, so 184 patients and the ClearVisc arm, and 188 eyes from 188 patients in the VISCOAT arm for a total of 372. And they were pretty well balanced, you know, because it’s randomized, so you you’d expect this, but pretty well balanced in terms of all the important characteristics like nuclear density, which of course is a big factor in endothelial cell density loss, right?
So for the FDA, the point is non-inferiority. Basically, we’re not looking to prove we’re better than control, we’re just looking to prove we’re as good as the current market leader. And that’s exactly what we did.
So basically if you look at the graphs that are presented in my presentation, you will see that the incidence of high pressure is almost identical between the two groups. If you look at baseline post-surgery, about 6 hours, we measured it 4-6 hours, which is when the peak pressure occurs, and then again, 24 hours later.
Before the operation, the average was around 15. On this 4-6 hour visit, the main pressure was 25, then the next day the average pressure was back to around 20.
So really very, very similar between the two groups, and also very, very similar in terms of endothelial cell loss. We saw about 8.4% in the ClearVisc group 6.8% in the VISCOAT group, and these were not statistically different.
So basically we showed that this new dispersive works as well as VISCOAT for protecting the endothelium and preventing IOP spikes postoperatively.
Adverse events were fairly balanced between the two groups. There’s nothing unexpected that happened, you know, no unusual rates of cystoid macular edema or iritis, which are things I know people are looking at because we’re using a new viscoelastic, you want to make sure it doesn’t cause any type of inflammatory reaction, and we certainly haven’t seen anything like that.
In conclusion, you know, ClearVisc met its main criteria of safety and efficacy, not inferior to VISCOAT. We now have a new option in cataract surgery, which is really exciting. It’s been quite a while. I think the most recent was EndoCoat, which was now a number of years ago. And so now we have a new option in viscoelastic dispersive for surgeons in the United States. Thanks a lot.
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