Nathan Radcliffe, MD: New Surgical Instrument Allows for Simultaneous Cataract and Glaucoma Surgery
NOVEMBER 16, 2017
Nathan Radcliffe, MD, New York Eye and Ear Infirmary, Mount Sinai:
The technique that we were using is called the Kahook Dual Blade, is actually invented by my friend whose name is Malik Kahook, it's been fun to watch him develop this new treatment and it's unique in a couple of ways. In this study we had 71 patients who underwent this surgery, done at the same time as a cataract surgery. The the issue with glaucoma, is that we have a lot of patients who have coexisting glaucoma and cataract, and they come into their cataract surgery, they're on a lot of medications and they also usually have pressures that are higher than we want. Of course the intraocular pressure is the driving force of progression for glaucoma so we want to lower the intraocular pressure, keep it as low as possible. We use drops when we have to, but we always prefer to get people off their drops, or on as few drops as possible.
In our study, we had 71 patients who underwent a cataract extraction at the same time this goniotomy procedure with the Kahook dual blade. The way the procedure works is after the cataracts been removed, an instrument that has 2 small blades, really micro blades, is used to enter the canal of schlemm, which is the internal drainage pathway of the eye, and excise the trabecular meshwork. You can actually remove it from the eye, so you're really removing this tissue that serves as the site of resistance for the egress of fluid from the eye.
In this study, there were many centers, many surgeons involved, for most of us with some of our first cases. It's always good to have that data because you not only get the learning curve in terms of safety, but efficacy too. So if a procedure looks good, and you have data from the learning curve, that's usually a good sign that you'll either have a safer experience once people get comfortable with it, or better efficacy if they get more effective at doing a surgery.
Starting with the intraocular pressure, what we saw in our 71 patients is that the baseline pressure was around 17.4 mmHg. And as we carried out to 12 months, we got the pressure down to just 12.5 mmHg — so significant difference. You know with some of these surgeries, now the cataract was part of that too, and we know cataract surgery lowers pressure a little bit, but that's a good bit of pressure reductions about 5 mmHg.
With these safe glaucoma surgeries, sometimes we see a little bit less than that. So this is at least encouraging, and you know we're sort of enthusiastic about the efficacy of the procedure. The other thing you you think about with efficacy though, is not just getting the pressure down, but reducing the number of meds. And patients were on about 1.6 medications on average at baseline and we got that down to 0.8 — so less than 1. So that means a lot of people did actually get off their drops, which is you know what you would call an unqualified success, assuming the pressure was controlled as well. So again, good reduction in pressure and good reduction in number of medications — the 2 things we're going for with the surgery.