More comprehensive ophthalmologists should offer MIGS with cataract surgery
Click Here to Manage Email Alerts
The accompanying cover story is a good summary of the current microinvasive, or minimally invasive, glaucoma surgery devices.
This is an area of research, development and investment that I have participated in actively for more than 20 years, ever since Glaukos was founded in 1998, so I do have several disclosures to make (see below). I would like to make a few observations that are general in nature and pertain to the entire MIGS field.
First, the base of the pyramid of MIGS is cataract surgery itself. Cataract surgery remains the most common surgical procedure performed by ophthalmologists worldwide, with more than 4 million procedures performed each year in the United States alone and more than 28 million globally, according to Market Scope. Cataract surgery, with or without an IOL implant, lowers IOP significantly and permanently. The amount and duration of IOP lowering varies by type of glaucoma, race and study reported, but in the Glaukos iStent FDA clinical study at 1 year, IOP lowering with phacoemulsification and posterior chamber IOL placement was a lofty 8.2 mm Hg. This data and several other studies confirm that removal of the natural lens, clear or cataractous, is a powerful tool in the reduction of IOP.
Another interesting finding is that 15% to 20% of the population presenting to U.S. ophthalmologists for cataract surgery also have ocular hypertension or glaucoma, according to CMS data. While cataract surgery alone can benefit these patients in regard to IOP reduction, the addition of a MIGS procedure at the time of cataract surgery has a benefit. This fact leads me to believe that 600,000 to 800,000 patients a year in the U.S. and more than 4 million globally would benefit from combining MIGS with their cataract surgery every year, as they are already in the OR for the cataract procedure and the addition of MIGS is straightforward.
So, why not add MIGS to their surgery? One reason would be increased complications and/or patient morbidity, but leaning on the Glaukos iStent FDA clinical trial again, the addition of MIGS to cataract surgery did not increase the complication rate or patient morbidity as compared with cataract surgery alone. Other factors, including surgeon training and cost, are clearly playing a role, but a virtuous goal to me would be for every patient who presents for cataract surgery with glaucoma to be offered the addition of a MIGS procedure while they are in the OR for cataract surgery. We are well short of this goal even in the United States, where training and cost should be less of an issue, with less than 30% of those who might benefit from a MIGS procedure at the time of cataract surgery receiving it. Therefore, my second observation is that we should be doing more MIGS procedures each year than we are — perhaps three to four times as many as we do today.
Finally, there is an interesting difference in how glaucoma specialists and comprehensive ophthalmologists manage glaucoma surgically. I believe there is a difference between the average severity of the glaucoma managed by these two groups, and this explains some of the difference, but not all of it. Rounding off the numbers, according to Market Scope, about 600,000 laser procedures, 200,000 MIGS procedures and 100,000 tube shunts or trabeculectomies are done each year in the United States. There are about 8,000 active cataract surgeons and just more than 1,000 fellowship-trained glaucoma specialists in the U.S.
Looking at the 600,000 laser procedures for glaucoma, it is interesting that glaucoma specialists perform 60% of them and comprehensive ophthalmologists, who outnumber them 8 to 1 and see many more glaucoma patients, perform only 40%. This suggests to me that the comprehensive ophthalmologist is not offering a laser procedure, especially selective laser trabeculoplasty, as often as they might. Of the two groups, the cataract surgeon does twice as many MIGS procedures as the glaucoma specialist, but considering the number of surgeons involved, they should likely be doing four to five times as many. The issue here is that many comprehensive ophthalmologists are not offering MIGS to their patients with glaucoma when they are scheduled for cataract surgery. I believe this is an area in which the comprehensive ophthalmologist needs to improve. Finally, glaucoma specialists perform 95% of the tube shunts and trabeculectomy procedures in the U.S., and this to me is logical and appropriate as the patients being seen have more advanced glaucoma, and tube shunts and trabeculectomies are much more invasive with significant postoperative complications and patient morbidity. Well-performed registry studies in the cardiovascular field suggest that to be highly proficient at a surgical procedure, a surgeon must perform it 50 or more times a year in a center where it is performed 200 or more times a year. It is the rare comprehensive ophthalmologist who achieves this volume of tube shunts or trabeculectomies, and for most of us, these two procedures are best performed and managed by the fellowship-trained glaucoma specialist.
In summary, cataract surgery alone is an excellent glaucoma procedure, but cataract surgery plus MIGS is even better at reducing IOP and medication burden. We can and should be doing more MIGS in our cataract patients in the U.S. and globally. Data also suggest the comprehensive ophthalmologist is not performing SLT frequently enough. Performing more SLT and MIGS procedures is a win for the patient with glaucoma and a win for the ophthalmologist performing them. Finally, for most of us, it is best to refer the patient requiring a tube shunt or trabeculectomy to a fellowship-trained glaucoma specialist who is performing one or more of these more complex procedures a week.
Collapse
Click Here to Manage Email Alerts