Selective laser trabeculoplasty (SLT) is a safe and effective first-line treatment for newly diagnosed open-angle glaucoma, Eileen Bowden, MD, told the audience at the American Glaucoma Society’s annual meeting last week in Washington, DC. Dr. Bowden, an assistant professor of ophthalmology at the University of Texas at Austin, reviewed 6-year data from the Laser in Glaucoma and Ocular Hypertension (LiGHT) trial during Saturday’s “Clinical Application of Results from Randomized Clinical Trials in Glaucoma” symposium. According to Dr. Bowden, the data indicates that SLT may not only control intraocular pressure (IOP) but may even “have positive impacts on disease progression and, compared to medical therapy, may reduce the need for cataract surgery and even incisional glaucoma surgery.”
The LiGHT Trial
LiGHT was a randomized control trial conducted in the United Kingdom which included 718 treatment-naïve subjects newly diagnosed with ocular hypertension or primary open-angle glaucoma. (Subjects with advanced disease, angle-closure glaucoma, childhood glaucoma, or secondary glaucoma were excluded from the study.) Outcomes included health-related quality of life (Figure 1), cost effectiveness, and clinical efficacy.1
Figure 1. The mean values for the health-related quality of life (HRQoL) questionnaires across the 72 months are shown here. No significant difference was found between the two treatment arms for the EQ-5D, GUI, and GQL-15 scores. For GSS scores, the medication group showed worse scores at 72 months, but this was the only time point at which a notable difference was observed. Image courtesy Eileen Bowden, MD.
A target IOP was set for each patient, based on the severity of their disease, and this target was adjusted through the course of the trial according to the absence or presence of disease progression, Dr. Bowden explained. Subjects were then randomized into 1 of 2 treatment pathways: either initial treatment with laser trabeculoplasty or treatment with IOP-lowering drops. “In the laser-first arm, those patients received SLT in a standardized fashion. They had 360° of their angle treated using 100 non-overlapping shots, and SLT could be repeated once in these patients if they failed treatment,” explained Dr. Bowden. “In the drop-first arm, patients received a single drug at initiation and the drug classes for first-line, second-line, and third-line therapy were determined based on NICE [National Institute for Health and Clinical Excellence] and EGS [European Glaucoma Society] guidelines.”
Baseline characteristics between the 2 groups were similar, said Dr. Bowden, with a large proportion of participants being white. Of the 692 subjects who completed the initial 3-year trial, 633 (91.5%) continued into a trial extension, in which subjects in the laser-first arm could undergo a third and final SLT prior to escalating therapy and switching to medical therapy. Those in the drop-first arm were permitted to undergo SLT if they wished to reduce their medication burden, to avoid adding another medication, or to delay surgery. A total of 524 patients completed 3 years of the trial extension.2
Figure 2. Visual acuity and virtual field mean deviation loss at 72 months were similar between the 2 treatment arms. Image courtesy Eileen Bowden, MD.
Six-year Results
Throughout the 72-month study period, patients in the SLT-first group maintained comparable visual acuity and visual field preservation to those in the medication-first group (Figure 2). Nearly 70% of eyes in the SLT-first group achieved drop-free IOP control (Figure 3). Among these, 90% had undergone 1 or 2 SLT treatments. Although the drop-first group had a lower mean IOP at 6 years, the laser-first group showed reduced disease progression compared to the drop-first group.
An analysis of visual field changes found that 1 in 4 eyes in the drop-first group exhibited moderate or fast disease progression, compared to 1 in 6 in the SLT-first group. “This raises the question of whether there’s another protective role or protective mechanism of SLT apart from IOP lowering,” noted Dr. Bowden. “The laser-first group also needed fewer trabeculectomies, so the greater number of incisional glaucoma surgeries in the drop-first group may explain why there was a somewhat lower IOP in this group at 72 months, compared with the eyes initially treated with SLT. Finally, the medicine-first group were more likely to need cataract surgery during the trial.”
Figure 3. The percentage of visits with eyes at target pressure was similar between the treatment arms. The laser-first group achieved drop-free IOP control in almost 70% of eyes, had reduced objectively defined disease progression compared to the medicine-first group, and needed fewer trabeculectomies than the medicine-first group. Image courtesy Eileen Bowden, MD.
Economic analysis favored SLT as the more cost-effective treatment in the United Kingdom’s National Health Service (NHS), she said. The laser-first approach required fewer medications and surgeries over time, reducing the financial burden on the health care system.
Adverse events were minimal, with no sight-threatening complications reported. In the laser group, IOP rose more than 5 mmHg in only 1% of eyes. Patients receiving medication reported more side effects, including periocular pigmentation, lash growth, and ocular discomfort.
The trial also examined the efficacy of repeat SLT treatments. Of 115 eyes that initially failed SLT within the first 18 months, a second SLT resulted in sustained IOP reduction. Eyes that underwent repeat SLT were more likely to have moderate or severe POAG at baseline compared to those controlled with a single treatment.
Evolving Paradigm
These results have driven a paradigm shift in the United Kingdom regarding glaucoma care, where the NHS has adopted an SLT-first approach to glaucoma patients, said Dr. Bowden. In the United States, the American Academy of Ophthalmology’s preferred practice pattern recommends SLT as either first-line or adjunctive therapy.
“In my own practice I do follow these guidelines, and when I’m faced with a patient that has similar demographics to those that are included in the LiGHT trial, I often do offer laser first,” said Dr. Bowden. “I include the line in my counseling that if I was in their position, that’s the treatment that I would choose for myself.”
During the question-and-answer period following the presentation, Dr. Bowden noted that during the trial, there were at least 34 eyes that failed to respond to an initial SLT treatment, but that showed good pressure control after a second SLT treatment. “I like to wait at least 2 months after the first SLT to evaluate its response,” she said. “But after that, especially if there was a little bit of an initial response and then it failed, I am in favor of repeating SLT after 2 months.” GP
References
1. Gazzard G, Konstantakopoulou E, Garway-Heath D, et al. Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial Lancet. 2019;393(10180):1505-1516. doi:10.1016/S0140-6736(18)32213-X
2. Gazzard G, Konstantakopoulou E, Garway-Heath D, et al. Laser in Glaucoma and Ocular Hypertension (LiGHT) trial: six-year results of primary selective laser trabeculoplasty versus eye drops for the treatment of glaucoma and ocular hypertension. Ophthalmology. 2023;130(2):139-151. doi:10.1016/j.ophtha.2022.09.009
