~Doctor, I Have a Question. What is the Role of MIGS Procedures in a Doctor’s Arsenal of Treatment Options?
Question answered by:
There is a real role for minimally invasive glaucoma surgeries (MIGS), but we have to have realistic expectations going in.
Every glaucoma procedure has an efficacy side and a safety side and there’s a continuum of surgeries that range from being highly effective pressure reducers that carry many more safety risks, to those that are very safe but provide modest pressure reduction.
The great advantage of MIGS as compared to traditional surgery like a trabeculectomy or a drainage implant is safety. MIGS don’t have nearly the frequency or severity of complications as, for example, a trab, but in the long term, they don’t appear to have the efficacy of the procedures that have a greater complication profile.
Here’s how MIGS work to lower intraocular pressure. Some, like the iStent and Hydrus, target the trabecular meshwork (TM), which is the conventional aqueous humor outflow path but which is often blocked in glaucoma. Both the iStent and Hydrus lower IOP by creating a bypass through the trabecular meshwork (TM) allowing aqueous to go directly into the Schlemm’s Canal. Another strategy is to incise the trabecular meshwork with a blade or with a filament threaded into Schlemm’s canal (Sight Sciences Omni 360) or remove a segment of the trabecular meshwork with a device such as Kahook Dual Blade.
There are outflow pathways beyond the TM. There is a strategy of instilling viscoelastic through the TM into Schlemm’s canal to dilate the outflow pathways. The Sight Sciences Omni 360 is designed to do this in addition to TM incision.
Both the iStent and Hydrus – like some other MIGS devices – were tested and approved by the FDA for implantation only in combination with cataract surgery. While there’s no reason these devices wouldn’t work as stand-alone procedures, they would not be covered by insurance as they would be “off-label” procedures.
Only the Xen Gel Stent, a different category MIGS device, which diverts the fluid from inside the eye to the subconjunctiva space, (more like what a trabeculectomy does) is a device approved in the United States for implantation alone or with cataract surgery.
Patients with mild or moderate glaucoma can have confidence about any of these devices as they all seem to be roughly similar in lowering IOP. For whom would they be recommended?
Let’s say, for example, that you have mild glaucoma with a little bit of damage but you are controlling your pressure very well with two eye drops. When we do your cataract surgery, which by itself often lowers IOP, we can do an additional MIGS procedure for you that may further help your pressure control or may get you off one or two drops – at least for a while.
Or, we could just do the cataract surgery and you’ll likely be on the same two drops afterward.
It makes sense to me to offer a MIGS procedure if I can help you get better pressure control or reduce the burden of eye drops – to me that’s a victory. It may seem like a small victory, but for glaucoma, we celebrate any victory.
MIGS procedures and devices, however, will not replace a trabeculectomy or a glaucoma drainage implant when that’s what you need.