Trabeculectomy effective but presents problems
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Approximately 3 million Americans carry the diagnosis of glaucoma. At 5 years after diagnosis, approximately 5% require invasive surgical intervention.
According to a paper published in Clinical Ophthalmology, 174,788 glaucoma surgeries were performed in patients 65 years and older in 2017. The majority, 131,935 (75.5%), were classified as microinvasive glaucoma surgery. Trabeculectomy was performed in 22,862 patients (13.1%) and a tube shunt in 19,991 patients (11.4%).
The original iStent (Glaukos) was approved by the FDA in 2012, creating the MIGS vertical, which now dominates glaucoma surgery. Based on several iStent and Hydrus (Alcon) publications, the expected IOP outcome of cataract surgery combined with a trabecular bypass MIGS procedure is approximately 18 mm Hg on one topical medication at 5 years after surgery.
Some of our best information on trabeculectomy and tube shunt surgery comes from the Tube Versus Trabeculectomy Study in which 17 highly experienced glaucoma surgeons enrolled 107 patients to receive Baerveldt tube shunts and 105 patients to receive trabeculectomy with mitomycin C in a randomized prospective clinical trial. This level I clinical evidence reported that 5 years after surgery, the mean IOP on 1.4 topical glaucoma medications after tube shunt surgery was 14.4 mm Hg. The mean IOP on 1.2 topical medications after trabeculectomy surgery was 12.6 mm Hg. Both trabeculectomy and tube shunt surgery resulted in a significantly lower IOP than cataract surgery plus MIGS. Trabeculectomy surgery generated the lowest IOP. On the negative side, complications were much higher for both trabeculectomy (18%) and tube shunt (22%) than cataract surgery plus MIGS. Reoperations were also high at 29% for trabeculectomy, usually for encapsulated blebs, hypotony, secondary cataract and several sight-threatening complications including bleb infection. While not studied, every surgeon knows that the number of postoperative visits required is much higher for trabeculectomy than for cataract surgery plus MIGS.
For the phakic patient who requires an invasive glaucoma surgery, cataract surgery plus MIGS is a wise first choice if a target pressure of 18 mm Hg is deemed adequate. But, as discussed in the accompanying cover story, if an IOP target in the 10 mm Hg to 13 mm Hg range is desired, a trabeculectomy remains the procedure of choice. Since it was pioneered by Peter Watson and John Cairns in the 1970s, trabeculectomy surgery remains a mainstay for the management of more severe cases of glaucoma. In my first 3 decades of practice, I performed many trabeculectomy procedures every month, often in combination with cataract surgery. Today, in our practice at Minnesota Eye Consultants, all our cataract surgeons perform MIGS, but only our glaucoma fellowship-trained partners are still performing trabeculectomy and tube shunt surgery.
Quality research in cardiovascular surgery has suggested that to be truly expert in a surgical procedure, a surgeon must perform it 50 times per year, and the surgery centers with the best outcomes perform a procedure at least 200 times per year. These volumes are easily attainable by the typical comprehensive ophthalmologist and every ASC for cataract surgery and approachable for MIGS, but with only about 23,000 trabeculectomies performed each year, if all 10,000 cataract surgeons engaged, they would only perform two to three trabeculectomy procedures per year. That is not enough for most surgeons to become expert and feel confident.
In addition, much like keratoplasty, reimbursement is arguably insufficient for the work and stress required when performing trabeculectomy. In 2023, the Medicare surgeon fee for a trabeculectomy is $1,090 and the ASC fee $1,101 for a total of $2,191 with time-consuming postoperative management. A cataract surgery plus trabecular bypass MIGS allows a surgeon fee of $683 plus an ASC fee of $3,245 for a total of $3,928 with a straightforward postoperative course.
While I believe every cataract surgeon should offer MIGS, those surgeons who accept the challenge of performing trabeculectomy surgery, like their cornea specialist colleagues who perform keratoplasty, are providing their patients, community and fellow ophthalmologists a great service. We and our patients are fortunate to have a strong cohort of fellowship-trained glaucoma specialists in the U.S.
- References:
- Gedde SJ, et al. Am J Ophthalmol. 2012;doi:10.1016/j.ajo.2011.10.026.
- Ma AK, et al. Clin Ophthalmol. 2020;doi:10.2147/OPTH.S257361.
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