Despite training challenges, trabeculectomy remains crucial
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For more than 50 years, trabeculectomy has been the gold standard in the management of severe glaucoma.
Even though glaucoma progression can generally not be reversed, trabeculectomy has demonstrated the ability to reduce IOP and slow progression. At a time when minimally invasive glaucoma surgeries have been in the limelight, trabeculectomy still stands alone, according to Louis R. Pasquale, MD.
Source: Leon W. Herndon Jr., MD
“Whether it’s ocular hypertension, early glaucoma or advanced glaucoma, we don’t have any evidence that anything we can do so far stops the disease,” Pasquale said. “If we are ever going to eradicate glaucoma blindness, we need an operation that gets pressure down to episcleral venous levels from the get-go. In my humble opinion, the operation that has the best chance to get the lowest eye pressures is trabeculectomy. I’m not sure it’s even debatable.”
Trabeculectomy is an invaluable tool to help patients who have higher IOP. Healio | OSN Associate Medical Editor Leon W. Herndon Jr., MD, has concerns that this critical procedure is falling by the wayside, particularly in training settings.
“In some cases, it’s not being taught anymore in favor of MIGS and glaucoma tubes,” he said. “I do a lot of MIGS and a lot of tubes, and I think they have their roles. However, it’s clear — and I don’t think anyone would argue — that trabeculectomy gets lower pressures than any other procedure we do.”
While trabeculectomy presents a list of potential complications, including infection, low pressure and cataract formation, Herndon said without trabeculectomy, the future for patients with severe glaucoma is bleak.
“The population is getting older, and there are going to be more patients with severe glaucoma,” he said. “In 10, 15 or 20 years, if you have relatively few people trained in doing trabeculectomy surgery, they might be able to do a nice MIGS procedure, but that’s not going to help these patients with advanced disease.”
Including trabeculectomy and end-stage glaucoma care in training programs might be difficult, but it is critical to secure the future of patient care.
Candidates for trabeculectomy
If training for trabeculectomy wanes, Pasquale said typical candidates for the procedure would not have an option that comes close to achieving the same benefit.
“It’s patients who have pressures in the mid-teens who are definitely getting worse, and they’re desperate,” he said. “The handwriting is on the wall, so to speak, and they’re losing ground.”
These patients are usually pseudophakic and have already undergone a MIGS procedure, Pasquale said. In these patients, studies have shown that trabeculectomy can slow the disease and preserve vision.
A study published in Eye analyzed data from 80 eyes of 74 patients who underwent trabeculectomy between 2015 and 2016 at network sites of Moorfields Eye Hospital in the United Kingdom to determine the procedure’s effect of rate of progression of visual field loss. Before surgery, the mean IOP was 18 mm Hg, and the mean rate of progression was –0.94 dB per year.
One year after surgery, the mean IOP was 10 mm Hg, while the mean rate of progression was slowed down to –0.32 dB per year. Pasquale said slowing down the rate of progression by that much makes a big difference for patients and their future visual outlook.
“If you think of the visual field like a bank, when the bank is full, you’ve got 30 dB of visual sensitivity,” he said. “If you lose a decibel per year from glaucoma, it’s going to take you 30 years to go blind. If you’ve already lost 20 dB and you’re 70 years old, there is a good chance that you will go blind in your lifetime. You could go blind by age 80.”
If patients undergo trabeculectomy to slow that progression, Pasquale said they have a better chance of preserving their vision throughout the rest of their lives.
Herndon said it is possible for patients with severe disease to be controlled with medication.
“If patients have a pressure in a tolerable range and they’re not having visual field loss progression, you can follow these patients medically,” he said. “I would say that the great majority of patients with severe glaucoma are able to be followed medically. I have a bit of a skewed population in my practice because I see a lot of patients who have failed medical or laser options, and they are getting worse. That is where trabeculectomy comes in.”
Herndon said trabeculectomy is his go-to when he wants to get a patient’s IOP to 12 mm Hg or lower with no medications.
In a 2021 study published in BMJ, a randomized controlled trial evaluated whether primary trabeculectomy or primary medical treatment produced better outcomes in quality of life, clinical effectiveness and safety in patients with advanced glaucoma.
Patients underwent mitomycin C-augmented trabeculectomy or escalating medical management with IOP-reducing drops. The primary outcome was vision-specific quality of life measured with the Visual Function Questionnaire-25 (VFQ-25) at 24 months. Secondary outcomes included glaucoma-related quality of life and clinical effectiveness.
At 24 months, the mean VFQ-25 scores were 85.4 in the trabeculectomy group compared with 84.5 in the drop group. However, patients in the trabeculectomy group had a lower mean IOP (12.4 mm Hg) compared with the drop group (15.1 mm Hg) (P < .001).
“Interestingly, there was really no difference between the two groups when it comes to quality of life,” Herndon said. “When we think of trabeculectomy, you have a lot more complications like irritations to the eye, but this study showed there really were no quality of life concerns.”
Issues with training
In an editorial published in Ophthalmology Glaucoma, among U.S. glaucoma fellows, the median number of primary trabeculectomy or Ex-Press shunt (Alcon) procedures was 49 in 2014-2015, according to the Association of University Professors of Ophthalmology Fellowship Compliance Committee. In 2018-2019, the median number of procedures was 32. Over the same time, primary surgeon ab interno angle procedures increased from zero to 12.
Kuldev Singh, MD, said there are several reasons why trabeculectomy is trending down in training. One is all of the new MIGS procedures that have been introduced over the last few years.
“Whenever new procedures come out, teaching doctors as well as residents and fellows want to try them out,” he said. “Clinical glaucoma fellowships are generally only for 1 year, so if those who are providing training are trying new procedures, they may be performing fewer trabeculectomies during that period. We need to be mindful of teaching newer as well as time-tested older procedures.”
Another factor is the time it takes to master the procedure.
“Trabeculectomy may not be as technically challenging as some other intraocular surgical procedures, but there is a learning curve,” Singh said. “It takes a pretty good length of time to perfect one’s technique, not to mention the postoperative care.”
It is difficult to teach trabeculectomy during the training period because of the intense follow-up that is needed, Pasquale said. A trabeculectomy is a wound, and the body wants to heal it, he said.
“You have to fight that process in a way that keeps the patient safe and keeps the anterior chamber formed,” Pasquale said. “When I’m looking at the patient, I’m looking at the bleb to see if it has crisscrossing blood vessels. It doesn’t matter how good the surgery was in the operating room. Crisscrossing blood vessels signify a bleb that will result in an IOP above episcleral venous levels, and we have to fight that, which is a day-to-day battle.”
During follow-up, Pasquale wants to see that the bleb is becoming avascular with microcysts in it.
“I have to see these patients two or three times in the first week, once or twice in the second week, and maybe once a week thereafter until I’m convinced that the operation is not going to fail,” he said. “I can coach a resident to do a good trabeculectomy, but it is the postop care on day 1, 3 or 5 that is critical, and residents can often miss out on that aspect of care due to conflicting responsibilities.”
Pasquale had one patient — a hospital administrator — tell him that he was losing money by performing a trabeculectomy on him because of the lengthy follow-up.
“I told him this is what I have to do to keep you with your eyesight,” he said. “I can’t help that they are not reimbursing me for it.”
In a world in which medicine is becoming increasingly transactional, Singh said many surgeons see trabeculectomy as too labor intensive.
“The practice of medicine is a business, and some practitioners may look at the time involved in performing a trabeculectomy along with the postoperative effort and just decide that it doesn’t make sense for them to offer this procedure,” he said. “They might prefer to use their time to do other things.”
These factors can create a cycle in which new ophthalmologists do not have the opportunity to see the surgery in action and have not had a chance to appreciate its value, Singh said.
“I am seeing many more patients with advanced disease who have been passed around from doctor to doctor without anyone recommending a trabeculectomy than ever before. For some, this unfortunate delay may have resulted in it being too late to preserve vision,” he said.
“With fewer and fewer trabeculectomies being performed overall, many trainees do not get a chance to see the power of this procedure,” he said. “New fellows sometimes walk out of the exam room in disbelief after seeing a patient with advanced glaucoma who has had single-digit IOPs and stable visual fields for 30 years and preservation of functional vision. While seasoned glaucoma doctors see these types of results all of the time, some of our trainees and younger colleagues say, ‘Wow, I didn’t think this was possible.’ I recall Dr. George Spaeth once saying, ‘You don’t know what you don’t know.’ If our next generation of glaucoma doctors do not see the power of trabeculectomy in their training, they will undoubtedly be less likely to learn the intraoperative and postoperative techniques required to get great outcomes with this procedure.”
No other procedure can achieve the same IOP levels offered by trabeculectomy, but that does not mean that a new option is not possible, Pasquale said.
“I’m sort of a cockeyed optimist. There have been a lot of disruptive technologies in ophthalmology throughout the years. Somebody somewhere could come out of left field with something that could get this done in a way that is safer than trabeculectomy,” he said. “The other side of that coin is that people have been looking for an alternative to trabeculectomy for 125 years, and no one has been able to find it.”
Hands-on trabeculectomy training
Until another operation that can safely achieve episcleral venous IOPs comes along, residency and fellowship programs will need to develop novel models to improve trabeculectomy training.
One such model is a glaucoma wet lab run by Tania Tai, MD, associate professor of ophthalmology at the Icahn School of Medicine at Mount Sinai and director of the glaucoma clinic at New York Eye and Ear. The program eases residents into surgeries by first having them practice on nonhuman eyes.
“For trabeculectomy, the most important parts of the procedure are knowing how to handle the conjunctiva and knowing how to make incisions in the sclera,” she said. “We have residents practice suturing conjunctiva, making partial-thickness incisions in the sclera and making scleral flaps in animal eyes before they get into the operating room to do these procedures on humans.”
Tai said there are two to three wet labs throughout the year so residents can learn every step of the trabeculectomy procedure as well as other procedures necessary for glaucoma management before they operate on a patient. However, learning these steps is not the complicated part, she said.
“The difficult part is to achieve a good patient outcome, meaning good vision and sustained pressure after the surgery,” she said. “The problem with trabeculectomy is that it doesn’t have a device, which can also be its benefit. With a device, you have a set size and a set outflow. They all have a certain size that limits the possibility of hypotony while still allowing flow. With trabeculectomy, what you’re relying on is your knowledge and your ability to handle the ocular tissue and patient healing.”
Tai said a surgeon needs to have a sense of how big of a flap to make during the procedure, as well as other factors such as how much mitomycin to use. They also need to know how to use postoperative medications, sutures and needles to manage healing.
“You’re relying on the surgeon’s experience and skill when you’re doing a trabeculectomy,” she said. “In my opinion, it takes more practice to get a trabeculectomy to be successful than an aqueous shunt, for example.”
To instill the importance of follow-up care, the program has residents follow their surgeries postoperatively. Patients might see different attendings per day, but they will see the same group of ophthalmologists every week and have continuity of care throughout their follow-up.
“Our rotations are about 6 weeks, so if they did trabeculectomy, they’ll follow up those patients throughout that rotation,” she said. “We also encourage residents to keep track of their postop even if they’ve rotated off the glaucoma rotation.”
Pasquale said it is critical for institutions to keep surgeons engaged in performing trabeculectomies and for new surgeons to find mentors to show them the right way to do the procedure from the beginning to the end of follow-up.
“I trained in a place where there were no glaucoma specialists, and I made so many mistakes early on,” he said. “I really only learned how to do trabs when I was a fellow. ... It’s really helpful to have a good role model. I had several: Dr. Harry Quigley, Dr. Jan Powell, Dr. Alan Robin, Dr. Irv Pollack. When I was a fellow, I learned from the masters. I got to work on their patients, and I learned so much from them.”
Moving forward with trabeculectomy
Tai said it is important to continue to encourage new surgeons to learn trabeculectomy.
“It’s an important message for us to give residents,” she said. “This is an important procedure that they need to practice and master. There are a lot of devices out there now — MIGS and aqueous shunts — and residents might get the sense that they don’t need this procedure. It’s still very important to get opportunities to operate and learn this procedure during residency and fellowship because these are the people who are going to be taking care of the complicated glaucoma patients down the road.”
Herndon said he understands why comprehensive ophthalmologists might not want to put the time into performing and following up on trabeculectomy. However, they need to find a way to offer it to patients who need it.
“If you’re not doing trabeculectomy, it’s important that you have good communication with someone who is,” he said.
Pasquale is hopeful that an innovative technology that can achieve the same milestones as trabeculectomy is on the horizon and said he would start using such a technology immediately if it were to come along.
“If someone has got something, please let me know because I’ll take it,” he said. “It’s very frustrating to be a glaucoma specialist and watch some of these patients suffer vision loss from this disease.”
- References:
- Caprioli J, et al. Ophthalmology. 2016;doi:10.1016/j.ophtha.2015.09.027.
- King AJ, et al. BMJ. 2021;doi:10.1136/bmj.n1014.
- Koenig SF, et al. Eye (Lond). 2023;doi:10.1038/s41433-022-02312-y.
- Singh K, et al. Ophthalmol Glaucoma. 2021;doi:10.1016/j.ogla.2020.08.009.
- For more information:
- Leon W. Herndon Jr., MD, of Duke Eye Center, can be reached at leon.herndon@duke.edu.
- Louis R. Pasquale, MD, of Mount Sinai Hospital, can be reached at louis.pasquale@mssm.edu.
- Kuldev Singh, MD, MPH, of Stanford University, can be reached at kuldev.singh@stanford.edu.
- Tania Tai, MD, of New York Eye and Ear, can be reached at ttai@nyee.edu.
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