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| SLT proponents say lack of adherence to medication is most likely behind lesser outcomes vs. SLT in the LiGHT study. |
Glaucoma remains a leading cause of blindness worldwide, making early intervention crucial for slowing disease progression and preserving vision. Traditionally, medication-based therapy, particularly prostaglandin analogs, has been a cornerstone of treatment for newly diagnosed patients, due to its effectiveness and ease of use. However, adherence challenges, side effects and long-term costs have led to increasing interest in alternative strategies.
Selective laser trabeculoplasty has emerged as a compelling first-line treatment for glaucoma, offering a non-invasive, adherence-free approach to intraocular pressure control. Landmark studies, such as the LiGHT trial, have demonstrated its efficacy, challenging the long-standing reliance on topical medications. Yet, debate persists within the ophthalmology community regarding the durability of SLT’s effects and its role in initial glaucoma management. As evidence continues to evolve, clinicians must navigate these considerations to determine the best approach for their patients.
This article examines the ongoing discussion surrounding SLT and medical therapy as first-line treatments for glaucoma, highlighting the benefits and limitations of each approach. Leading glaucoma specialists share their insights on key factors influencing treatment decisions, including effectiveness, patient adherence, safety and cost. Additionally, we review the latest research shaping clinical practice and discuss how evolving guidelines may impact future treatment strategies. As the field continues to advance, staying informed on these developments is essential to ensure optimal patient care and outcomes.
Experts Weigh In
Glaucoma specialists continue to refine their approach to first-line treatment, balancing effectiveness, safety, patient adherence and long-term outcomes. Their perspectives provide a deeper understanding of how ophthalmologists integrate both modalities into individualized glaucoma care.
For Tony Realini, MD, MPH, professor of ophthalmology and visual sciences, and vice chair for clinical research at West Virginia University, the majority of his newly diagnosed glaucoma patients receive SLT as a primary therapy.
“Medical therapy has been used for more than 150 years, and despite its limitations—such as poor adherence and tolerability issues, including a nearly 50-percent prevalence of ocular surface disease with chronic use—it has remained the standard because a viable alternative simply didn’t exist,” he says. “Now, we do have an alternative, and not just a viable one, but a better one.”
The LiGHT study was a well-designed and adequately powered trial that clearly demonstrated that SLT provides better outcomes than medical therapy, according to Dr. Realini, who notes that this is almost certainly due to overcoming the non-adherence associated with medical therapy. “I believe that any patient, when given a choice and helped to understand that one treatment is better than the other, will always choose the better option.”
While a strong proponent of SLT as a first-line therapy, Dr. Realini recognizes that not every patient is a candidate. “My approach to SLT changed dramatically when I stopped looking for reasons to perform it and instead started looking for reasons not to,” he says. “Once I made that shift, SLT became my default recommendation—unless there was a compelling reason not to use it—and there are times when it’s not the best option.”
SLT is highly effective for primary open-angle glaucoma and several of the other secondary open-angle glaucomas, such as pseudoexfoliation and pigmentary glaucoma, he explains while noting that he’ll adjust his treatment protocol for these cases. It’s also useful for ocular hypertension and normal-tension glaucoma.
“However, there are situations where SLT isn’t the best first-line option. I use it with great caution in eyes with uveitis, and it may not be appropriate for certain secondary forms of glaucoma,” Dr. Realini says, while also noting that narrow angles can make the procedure technically difficult and, in some cases, are a contraindication to SLT. “Additionally, corneal haze or abnormalities that preclude a clear view of the angle can also be a contraindication.”
That said, according to Dr. Realini, the number of cases where SLT isn’t viable as a first-line treatment is relatively small. For the vast majority of patients, it remains a highly effective and practical option.
“Personally, I think I’d be doing my patients a disservice if I didn’t let them know that one treatment option is better than the other,” Dr. Realini says. “They may have legitimate reasons for choosing medications over laser, and I always respect that decision. Medical therapy is highly effective and safe, and we couldn’t manage glaucoma without it. But I believe patients should make their decision only after being fully informed that one treatment may be more effective than the other.”
The choice between selective laser trabeculoplasty and medical therapy as the initial treatment for glaucoma is influenced not only by clinical efficacy but also by health-care infrastructure, patient preferences and cost considerations. Rodolfo Bonatti, MD, an assistant professor of ophthalmology at the University of North Carolina at Chapel Hill Department of Ophthalmology, who has experience across three different countries—Brazil, Canada and the United States—has witnessed this firsthand.
“In Brazil (São Paulo), where I completed my ophthalmology residency, I primarily worked within the public health-care system. In this context, access to SLT was limited, so my preferred treatments were prostaglandin analogs (when available) or timolol, due to its lower cost and easy availability,” he recalls.
Comparatively, in Canada (Halifax, Nova Scotia), where Dr. Bonatti completed his glaucoma fellowship, SLT was the preferred treatment option since it was readily available and covered by the public health-care system. “Most patients were open to laser treatment and didn’t perceive it as invasive,” he says. “If a patient wasn’t interested in laser treatment, I would typically prescribe prostaglandin analogs, such as latanoprost, which most patients could obtain through their medication programs.”
Currently, Dr. Bonatti is back practicing in Chapel Hill, and has found that his first-line treatment is usually a prostaglandin analog, predominantly latanoprost drops. This medication is widely available, has a low side-effect profile and most patients find it manageable to use just once a day, he explains.
“Initially, I attempted to use SLT as the primary treatment, but many of my patients expressed concerns about the procedure being too invasive,” Dr. Bonatti notes, adding, “When I do SLT, I often pre-treat patients with prostaglandins for a month before the SLT. I feel that patients with lower IOP (less than 20 mmHg), tend to have fewer pressure spikes after treatment.”
Effective patient communication is essential when discussing first-line glaucoma treatment options, as the choice between SLT and medication can significantly impact long-term disease management. Patients may have concerns about laser therapy being too invasive or worry about the burden of daily eye drops. Addressing these concerns with clear, evidence-based explanations can help patients make informed decisions that align with their preferences, lifestyle and medical needs.
Dr. Bonatti typically starts patient conversations by explaining that they have two options: they can use eye drops every day or undergo a laser treatment that will last for three to five years, which can be repeated later if it proves effective.
“I then show them a cross-section image of the eye that illustrates the trabecular meshwork and explain that the laser will cause inflammation at the natural drainage site of the eye,” he says. “This inflammation will make the body clear debris from the area, which in turn increases the natural outflow of fluid. I also discuss the most common complication, which is excessive inflammation leading to pressure spikes.”
Henry D. Jampel, MD, the Odd Fellows Professor of Ophthalmology at the Wilmer Eye Institute, and a professor of ophthalmology at Johns Hopkins Medicine, always involves the patient in the decision-making process, explaining to them that there are two effective ways to lower eye pressure: eye drop therapy and office laser treatment.
“I describe the eye drops, typically a prostaglandin taken in the evening, and explain that laser treatment is quick and painless,” he says. “I mention that the laser has an 80-percent chance of lowering the pressure to a point where they won’t need drops, but it’s not a permanent solution. Fortunately, recent research suggests that the laser can be repeated.”
Dr. Jampel goes over the potential side effects of prostaglandin treatment, including iris color change in some individuals, lengthening of eyelashes and mild redness in a small percentage of patients. He also informs patients about the rare complications associated with SLT.
“I make it a point to mention these potential risks to every patient during our discussion. These complications include effects on the cornea and changes in refractive error. However, I also emphasize that in my many years of practice, I’ve only encountered a handful of such cases,” he says. “While rare, I believe it’s important for patients to be aware of these possibilities.”
Approximately a third of glaucoma patients in Dr. Jampel’s practice opt for SLT first. He’s found that some individuals are hesitant about SLT because it sounds intimidating. “They may refer to it as ‘laser surgery,’ but I clarify that it’s not a surgery, but an office procedure with no risk of infection or bleeding,” he notes. “I also reassure patients that choosing drops doesn’t rule out laser treatment in the future. If the drops don’t work, aren’t tolerated, or cause side effects, they can still opt for laser treatment. Ultimately, it’s about selecting the option that works best for the patient.”
In older patients, particularly those in their late 80s or beyond, Dr. Jampel tends to recommend SLT more strongly. “Many of these patients come to appointments with their adult children, and I’ll often say, ‘I really think it would be best to avoid starting a new medication, and that laser would be a better option for you,’” he says.
This is especially true for patients in assisted-living situations, where there’s less confidence that eye drops will be administered consistently, he notes. “In these cases, I strongly recommend laser treatment, and it’s generally well accepted by both the patient and their family.”
Ongoing Research
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| The COAST trial looks at SLT in treatment-naive patients as well as the best strategy for repeat laser treatments. Photo:Carina Torres Sanvicente, MD. |
As SLT gains traction as a first-line treatment for glaucoma, ongoing research aims to refine its application and long-term efficacy. The COAST trial (Clarifying the Optimal Application of SLT Therapy) is a pivotal, NIH-supported, multicenter, randomized study designed to address critical questions about SLT dosing strategies and repeatability.
Building on the landmark findings of the LiGHT trial, COAST seeks to evaluate the efficacy and safety of standard- versus low-energy SLT among patients with mild to moderate open-angle glaucoma or high-risk ocular hypertension, while also identifying the optimal energy level and timing for repeat SLT treatments.
Recognizing the increasing use of SLT in clinical practice, Dr. Realini, study chair of the COAST trial, and his fellow investigators, asked the question, “Is there a better way to perform SLT?” The procedure has remained largely unchanged since the late 1990s, he notes, while highlighting a growing interest in modifying certain treatment parameters, specifically the laser energy.
“Some advocate for higher energy, believing more is better, while others suggest lower energy to reduce damage and potentially allow more frequent repeat treatments,” he says. “A handful of studies have explored high versus low energy, but most have been retrospective and single-center.
The COAST trial is the first study to explore whether lower energy can achieve the same effects as standard energy, according to Dr. Realini. “Additionally, we’re investigating whether an annual low-energy booster, regardless of IOP, might help preserve trabecular meshwork health and function, instead of relying on the current standard of PRN retreatment, which is essentially a rescue therapy after the trabecular meshwork has become re-impaired and lost its ability to regulate IOP. In many areas of medicine, preventive maintenance is often more effective than reactive treatments, and COAST is designed to test whether that holds true for SLT.”
COAST consists of two sequential studies: The first looks at initial SLT for treatment-naive or briefly treated patients, and the second evaluates the best strategy for repeat SLT. “The first trial was stopped early because we were able to answer our question more quickly than anticipated,” explains Dr. Realini. “The results, which have been presented at multiple meetings, revealed that standard-energy SLT was more effective than low-energy SLT in achieving and maintaining target pressure for 12 months.”
The investigators are now focusing on the second COAST trial, which compares PRN retreatment with standard energy when pressure rises, versus annual low-energy SLT as a booster, regardless of IOP, to preserve and maintain trabecular meshwork health and function. Enrollment for this three-year study is expected to be completed within the next 12 months.
“One of the challenges with SLT is that it works very well for most patients, and even when its effects wear off, we can often repeat the procedure with continued success,” notes Dr. Realini while discussing the goal of this research effort. “However, there comes a point at which SLT is no longer effective, where the patient stops responding, and we must transition to other therapies. This can happen after one, two or even three SLT treatments, varying from person to person.
“We believe SLT exhaustion occurs because, although SLT is much gentler on the trabecular meshwork than argon laser trabeculoplasty, it still causes some tissue damage, which accumulates over time with repeated treatments,” he adds.
Dr. Realini and colleagues hope that a low-energy maintenance treatment once a year could help preserve trabecular meshwork function and maintain IOP control with minimal additional damage, ultimately delaying the need for medications. “The ‘holy grail’ of glaucoma therapy would be to provide patients with a drop-free lifetime of disease management. If we can extend the time before SLT exhaustion occurs and keep patients responsive to SLT for a longer period, we move closer to achieving that goal,” he says.
A Shifting Paradigm
As glaucoma treatment continues to evolve, effective patient communication and education remain essential. By addressing concerns and clearly presenting treatment options, ophthalmologists can empower patients to make informed decisions and improve long-term outcomes.
Dr. Bonatti emphasizes that SLT is the most cost-effective first-line treatment for primary open-angle glaucoma and believes “we should prioritize its use as the initial treatment option.” However, he acknowledges that patient perception plays a role in decision-making, noting, “One limitation I have observed is how patients perceive ‘laser treatment.’ In my experience, patients in the United States tend to be more apprehensive about lasers compared to those in Canada or Brazil.”
Dr. Realini shares a similar perspective, strongly advocating for SLT as first-line therapy. “Given the advantages of SLT over medications—including lower progression rates, reduced risk of glaucoma surgery, elimination of medical therapy side effects and overcoming high rates of non-adherence—it’s my preferred first-line therapy.”
He also highlights the global shift toward laser-first treatment. “I’m not the only one who thinks so,” he says. “In the United Kingdom, the National Health Service has now adopted an SLT-first approach to glaucoma treatment unless there’s a specific reason not to. In the United States, we don’t have a national health system that dictates practice patterns, but we do have the American Academy of Ophthalmology, which publishes preferred practice patterns for primary open-angle glaucoma. Over the past 15 years, their recommendations on trabeculoplasty have evolved from suggesting it only for patients who cannot use medications, to considering it as an alternative to medications, to now recognizing it as a first-line therapy. The world is figuring this out.”
Drs. Realini, Jampel, and Bonatti report no relevant disclosures. Dr. Jampel is the Editor-in-Chief of the journal Ophthalmology Glaucoma.
