Best way to treat Glaucoma: drops or laser first?

Laser First? 6-Year Study Confirms SLT Beats Eye Drops for Protecting Your Vision in Glaucoma

By Dr. Sandra Lora Cremers, MD, FACS  |  EyeDoc2020  |  Visionary Eye Doctors, Rockville, MD

Quick Summary for Patients: A major 6-year clinical trial found that starting glaucoma treatment with a laser procedure called SLT — rather than daily eye drops — did a significantly better job at slowing vision loss over time. This is important news for anyone newly diagnosed with glaucoma or ocular hypertension.

What This Study Is About

Researchers recently published 6-year follow-up results from the LiGHT trial (Laser in Glaucoma and Ocular Hypertension Trial) — one of the largest and most carefully designed glaucoma treatment studies ever conducted. The original 3-year results already showed that SLT (Selective Laser Trabeculoplasty) was more cost-effective than drops and kept most patients drop-free. This new publication extends the look to 6 years and examines something even more important to patients: How fast did their vision actually change?

Two Groups, One Question

The study compared 710 eyes from patients newly diagnosed with either ocular hypertension (OHT — elevated eye pressure without vision loss yet) or open-angle glaucoma (OAG). Patients were randomly assigned to one of two groups:

• SLT-first group: Laser treatment as the initial therapy
• Drops-first group: Daily IOP-lowering eye drops as the initial therapy

Both groups were carefully monitored, and both were treated to their target eye pressure — meaning doctors escalated treatment when needed. This makes the comparison especially meaningful: it's not that the drops group was undertreated.

What They Found — The Numbers That Matter

Both groups achieved very similar average eye pressures during the 6 years (about 16–17 mmHg). Yet despite that, the SLT group had significantly less visual field loss:

• In the drops-first arm, patients lost an average of −0.37 dB/year of visual sensitivity
• In the SLT-first arm, the loss was only −0.26 dB/year
• This difference was statistically significant (p = 0.007) and was most pronounced in mild OAG patients

In plain terms: the laser group retained more of their visual field over 6 years, even though both groups had similarly controlled eye pressure numbers. This suggests SLT may offer benefits beyond just lowering pressure — perhaps by improving how fluid drains from the eye in a more physiologically natural way.

🔑 Key Takeaway for Patients If you have been newly diagnosed with elevated eye pressure or early-to-moderate glaucoma, this study strongly supports asking your eye doctor about SLT as a first-line option — before starting daily eye drops. The laser procedure is done in-office, takes only a few minutes, is generally well tolerated, and may preserve your vision better over the long term.

What Is SLT and How Does It Work?

SLT stands for Selective Laser Trabeculoplasty. It uses a low-energy laser to gently stimulate the eye's natural drainage tissue (the trabecular meshwork), encouraging better fluid outflow and lowering eye pressure. Unlike older laser procedures, SLT targets only specific cells without damaging surrounding tissue, which means it can generally be repeated if needed. The procedure typically takes 5–10 minutes in-office, is done with just numbing eye drops, and causes little to no discomfort for most patients.

Why Does This Matter Even When Eye Pressure Is Controlled?

One of the most fascinating aspects of this study is that both groups achieved similar average eye pressures — yet the SLT group still had less vision loss. This tells us something important: the way we control eye pressure may matter, not just the number we achieve. Scientists believe SLT may provide steadier, more consistent pressure control over time compared to drops, which can vary depending on patient adherence, medication absorption, and daily fluctuations.

What About Eye Drops?

Eye drops remain a very important and effective treatment for glaucoma. Many patients do well on drops, and they remain essential when SLT alone is insufficient or when patients are not candidates for the laser procedure. The key message from this study is about sequence: for newly diagnosed patients, starting with SLT rather than drops appears to offer a meaningful vision-protective advantage over time.

It is also worth noting that at 3 years, 74% of SLT patients in the original LiGHT study were still drop-free — a significant quality-of-life benefit, given the cost, inconvenience, and side effects that can come with long-term eye drop use.

The Bottom Line

This 6-year data from the LiGHT trial represents some of the best evidence we have in glaucoma care. The conclusion from the authors is clear: SLT should be preferred as the first-line treatment in newly diagnosed ocular hypertension and open-angle glaucoma.

As a glaucoma surgeon, I find this compelling and consistent with what I've observed clinically. If you have been recently diagnosed with elevated eye pressure or early glaucoma, I encourage you to have a conversation with your eye doctor about whether SLT is right for you.

📋 Questions to Ask Your Eye Doctor "Am I a candidate for SLT as a first treatment?"  |  "What are the risks and benefits compared to starting drops?"  |  "If I start with SLT, will I still need drops later?"  |  "How many times can SLT be repeated?"

Reference: Montesano G, Crabb DP, Garway-Heath DF, et al. "Six-Year Rate of Visual Field Progression in the Laser in Glaucoma and Ocular Hypertension Trial." Ophthalmology. 2025;133:169–177. doi:10.1016/j.ophtha.2025.09.023. Open access under CC BY 4.0.

This post is for educational purposes only and does not constitute medical advice. Please consult your ophthalmologist or glaucoma specialist to determine the best treatment plan for your individual situation. Dr. Sandra Lora Cremers practices at Visionary Eye Doctors in Rockville, MD and is affiliated with Johns Hopkins Medicine at Suburban Hospital.