Report Shows Minimally Invasive Glaucoma Surgery Rates Growing, Even Among Nonspecialists

Photo Essay From Clinic. (Photo By BSIP/UIG Via Getty Images)
Minimally invasive glaucoma surgery rates surged from 2008 to 2016, but only a quarter of procedures were performed by glaucoma subspecialists.

The substantial rise in minimally invasive glaucoma surgeries (MIGS) since 2012 is in large part due to its enhanced safety — and at the same time; considerably more clinicians who are not glaucoma subspecialists are performing the procedures, according to a report published in Ophthalmology. The study reviewed longitudinal trends in glaucoma treatments from January 2008 to December 2016.

During the study period, 1,468,035 fee-for-service Medicare beneficiaries in the United States underwent 1 or more incisional or laser glaucoma surgeries. Investigators who conducted the retrospective research chose a random 20% of the total procedures for analysis and multiplied the statistical results by 5 to obtain a representative sample. Including MIGS, the overall number of therapeutic glaucoma treatments received by patients enrolled in Medicare during the study period increased by almost 14.7%.

For traditional surgeries, glaucoma subspecialists continue to perform 75% to more than 80% of trabeculectomies and glaucoma drainage-device implantations (GDIs). Notably, researchers found that trabeculectomy decreased from 25,610 in 2008 to 18,925 in 2016, about -26.1%, although GDIs rose by 20.2%. Total MIGS grew from 2012 to 2016 by 426%.

“An unexpected finding is that such a large proportion of MIGS is being performed by nonsubspecialists,” according to the investigators. In fact, goniotomies increased by 1911.1% from 2008 to 2016, with these surgeries performed by nonsubspecialists 29.6% of the time at the start of this period, rising to 43.1% in 2016. Canaloplasties grew by 797.2%, with nonsubspecialists leading the procedure 16.7% of the time in 2008, climbing to 37.2% by the conclusion of the data analysis. 

Clinicians not specializing in glaucoma carried out laser trabeculoplasties 71% of the time in 2016. Further, transscleral cyclophotocoagulation — not classified in the study as traditional or MIGS — more than doubled from 2015 to 2016, with procedures completed by those who are not subspecialists increasing from 29% in 2015 to 39.8% in 2016, according to the investigators. With this expansion in glaucoma procedures, researchers recommend that all ophthalmology residents receive increased training in slit lamp gonioscopy to reach high comfort levels in the operating room.

In the current study, investigators defined “nonsubspecialists” as ophthalmologists and optometrists who completed at least 1 incisional or laser procedure, but less than 10 incisional glaucoma surgeries annually. They further validated their classification method by selecting a subset of 100 NPIs; comparing the providers’ glaucoma fellowship training status. 

Previous studies have examined trends prior to 2012, but 2012 marked the first year for MIGS codes. A limitation of the study was the absence of three newer MIGS procedures for which device-specific CPT codes were unavailable. Also, Medicare Advantage medical plan recipients were excluded due to incomplete information in the database. Only a sample of provider NPIs were validated for subspecialist status. However, the researchers noted, “the differences we are reporting between subspecialists and nonsubspecialists are likely underestimates of the true differences that exist.”

Disclosure: Several study authors declared affiliations with the biotech or pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Rathi S, Andrews CA, Greenfield DS, Stein JD. Trends in glaucoma surgeries performed by glaucoma subspecialists versus nonsubspecialists on Medicare beneficiaries from 2008 through 2016. Ophthalmol. 2021;128(1):30-38. doi:10.1016/j.ophtha.2020.06.051.