Why SLT for Glaucoma and how does it work?

Introduction

Selective Laser Trabeculoplasty (SLT) was first developed in the late 1990s by Dr. Mark Latina and Dr. Park as a novel approach to lowering eye pressure in glaucoma patients. Originally introduced as a second-line treatment to eye drops, SLT has evolved into a preferred first-line therapy for many types of open-angle glaucoma.

Scepticism surrounded SLT in its early years, but over time, robust clinical research—including the large-scale LIGHT study—has firmly established its effectiveness. This has led to a shift in clinical practice, with many eye care professionals, including Dr. Narain at South Bay Retina, now offering SLT as a primary treatment option for newly diagnosed glaucoma patients.

What Makes SLT Effective?

Most glaucoma studies define treatment success by the degree of intraocular pressure (IOP) reduction, which is the primary risk factor for disease progression. However, IOP is only part of the story. Long-term follow-up and advanced imaging techniques show that SLT not only lowers IOP but also slows or halts visual field loss, which is critical for maintaining sight.

Dr. Narain uses SLT as a first-line treatment in glaucoma management. His comprehensive approach includes:

• Automated perimetry

• Optical Coherence Tomography (OCT)

• Electrophysiologic testing

• Detailed clinical examination

Results from this multifaceted approach have been promising, with many patients showing stabilization of disease and, in some cases, improvement in visual function, even when the pressure changes are modest.

How Does SLT Work?

Here’s a step-by-step breakdown of how SLT lowers eye pressure and may support optic nerve health:

1. Targeting the Trabecular MeshworkSLT uses low-energy laser light to treat the trabecular meshwork, the drainage tissue responsible for fluid outflow in the eye.

2. Selective Stimulation of Pigmented CellsThe laser specifically stimulates pigmented cells without damaging surrounding tissues.

3. Biological RemodelingThis stimulation triggers a cascade of chemical and cellular changes, improving fluid drainage and lowering IOP.

4. No Structural DamageUnlike older laser treatments, SLT causes no scarring or permanent damage to the treated tissue.

5. Long-Lasting ResultsThe effects of SLT can last several years and the procedure can be repeated safely if needed.

6. Beyond Pressure, ControlSome patients experience normalized electrophysiologic parameters and improved microperimetry readings—indicating benefits beyond IOP reduction.

The Role of Cytokines and Cellular Mechanisms

SLT works in part through the release of cytokines, small proteins that play a critical role in inflammation and healing:

• Interleukin-1α, IL-1β, TNF-α, and IL-8 are key players in the remodelling of the trabecular meshwork.

• These cytokines help increase Schlemm's canal permeability and recruit immune cells, facilitating improved aqueous humour outflow.

• Gene expression studies have shown that SLT affects pathways related to cell motility, extracellular matrix remodelling, and oxidative stress.

SLT and Ocular Blood Flow: A Broader Impact?

Emerging research indicates that SLT may also influence ocular blood flow, possibly benefiting glaucoma patients beyond IOP reduction:

• Lowering IOP can enhance blood flow to the optic nerve head, potentially offsetting the effects of impaired autoregulation—a common issue in glaucoma.

• SLT may help restore more stable blood flow to the eye, improving tissue health and visual outcomes.

• Ongoing studies are exploring the relationship between SLT, photobiomodulation, and cellular recovery in glaucoma.

Why SLT May Be Better Than Eye Drops

SLT offers a number of advantages over traditional medication:

• No daily regimen – reduces patient burden and improves compliance.

• No systemic side effects – such as fatigue, heart rhythm disturbances, or mood changes.

• No ocular side effects – like eye redness, irritation, or changes in iris and eyelid pigmentation.

For many patients, SLT is not only more effective but also more convenient and safer than long-term use of eye drops.

Interested in SLT?

If you or a loved one has been diagnosed with glaucoma or are being treated with drops and want to explore alternative options, SLT might be the right fit.

📞 Contact us at South Bay Retina in San Jose for a comprehensive glaucoma evaluation.

🎧 Want to learn more? Check out our podcast episode: Understanding SLT Laser Treatment for Glaucoma (11 minutes)

FAQs

Q: How long does SLT last?: Typically, the pressure-lowering effect lasts 3–5 years, and the treatment can be safely repeated.

Q: Is SLT painful?: Most patients experience little to no discomfort. The procedure is done in the office and usually takes under 10 minutes.

Q: Can I stop using my drops after SLT?: Many patients can reduce or stop their drops after successful SLT, but this depends on individual response and disease severity.

If you're considering glaucoma treatment options, SLT offers a safe, effective, and evidence-based alternative to traditional eye drops.