Early observations and pilot data that first suggested a new direction
For decades, topical hypotensive eye drops were the unquestioned first-line treatment for open-angle glaucoma and ocular hypertension. Argon laser trabeculoplasty (ALT) emerged as an alternative in the 1990s, with the Glaucoma Laser Trial demonstrating that ALT was at least as effective as timolol drops for initial treatment. However, ALT caused permanent structural damage to the trabecular meshwork and had limited repeatability. Selective laser trabeculoplasty (SLT), introduced by Latina and Park in 1995, offered a gentler approach using low-energy Q-switched Nd:YAG laser that selectively targeted pigmented trabecular meshwork cells without thermal damage, suggesting it could be repeated.
Landmark RCTs and pivotal trials that established the evidence base
The LiGHT trial (Laser in Glaucoma and Ocular Hypertension) was a landmark multicenter RCT published in the Lancet in 2019 that compared SLT to eye drops as initial treatment for open-angle glaucoma and ocular hypertension. At 36 months, SLT achieved target IOP without drops in 74.2% of patients, and was superior to eye drops for IOP control at all time points. Critically, SLT was associated with fewer disease progression events, better cost-effectiveness, and improved quality of life due to the elimination of daily drop burden. This trial fundamentally challenged the drops-first paradigm that had dominated glaucoma management for over a century.
Follow-up studies, subgroup analyses, and real-world validation
The 6-year follow-up of the LiGHT trial confirmed the durability of SLT benefits, with 78% of patients initially treated with SLT remaining drop-free at 6 years, and repeat SLT successfully re-establishing IOP control in those who required retreatment. The SLT OPT trial further demonstrated SLT's effectiveness in a community ophthalmology setting. Economic analyses across multiple healthcare systems confirmed SLT's cost-effectiveness compared to drops, with annual savings driven by reduced medication costs and fewer clinic visits. Studies in diverse populations including patients with normal-tension glaucoma and pigment dispersion syndrome expanded SLT's applicability beyond the LiGHT trial population.
Integration into clinical practice guidelines and recommendations
Following the LiGHT trial, NICE updated its glaucoma guidelines in 2022 to recommend SLT as a first-line treatment option for newly diagnosed open-angle glaucoma and ocular hypertension, representing a major shift from the previous drops-first approach. The European Glaucoma Society guidelines now list SLT alongside prostaglandin analogues as appropriate first-line therapies. The American Academy of Ophthalmology Preferred Practice Pattern acknowledges SLT as a viable initial treatment, though uptake in the United States has been slower than in the UK and Europe. The shift has been described as one of the most significant changes in glaucoma management in decades.
NICE Guideline NG81 (Updated)
Offer SLT as a first-line treatment to people with newly diagnosed OAG or OHT. Discuss with patients the option of SLT before starting eye drops.
European Glaucoma Society Guidelines (5th Edition)
SLT can be offered as initial treatment for open-angle glaucoma with efficacy comparable to prostaglandin analogues.
Now
Current standard of care and ongoing research directions
SLT is rapidly becoming the preferred initial treatment for open-angle glaucoma in many healthcare systems, driven by the LiGHT trial evidence and updated guidelines. In the UK NHS, SLT-first has become standard practice in most glaucoma services. Challenges remain in ensuring adequate laser training for ophthalmologists, managing patient expectations about repeat treatments, and addressing the higher upfront cost of laser equipment versus drops. Research is ongoing into optimized SLT parameters, combination with minimally invasive glaucoma surgery (MIGS), and AI-assisted treatment planning. The paradigm shift from drops-first to laser-first represents a fundamental change in how glaucoma is managed worldwide.
The LiGHT trial was the first adequately powered RCT to compare SLT directly with eye drops as initial treatment. It showed SLT was not only non-inferior but superior to drops for disease control, with 74% of patients achieving target IOP without any drops at 3 years. It was also cost-effective, saving the NHS approximately 500 GBP per patient over 3 years.
Can SLT be repeated if it wears off?+
Yes, unlike argon laser trabeculoplasty, SLT does not cause permanent structural damage to the trabecular meshwork and can be repeated. The LiGHT 6-year data showed that repeat SLT was effective in maintaining IOP control, with 78% of patients remaining drop-free at 6 years including those who had repeat treatments.
Why has SLT adoption been slower in the United States compared to the UK?+
Several factors contribute: the US fee-for-service model financially incentivizes ongoing drop prescriptions over a one-time procedure, many US ophthalmologists were trained in a drops-first era, and insurance coverage for SLT as initial treatment varies. However, adoption is increasing as guideline bodies incorporate the LiGHT evidence and cost-effectiveness data accumulates.
