Home Eye Health Selective Laser Trabeculoplasty (SLT) as First-Line Glaucoma Treatment: Latest Evidence and FAQs

Selective Laser Trabeculoplasty (SLT) as First-Line Glaucoma Treatment: Latest Evidence and FAQs

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If you have been told you have ocular hypertension or open-angle glaucoma, the first decision often sounds simple: start pressure-lowering eye drops. But “simple” can turn into years of daily dosing, side effects, cost, and missed doses that quietly raise risk. Selective laser trabeculoplasty (SLT) offers a different starting point: a brief, in-office laser procedure that targets the eye’s natural drainage system to lower intraocular pressure (IOP), often with little or no ongoing medication. What makes SLT especially relevant today is the growing focus on long-term disease control—steady pressure, fewer treatment changes, and fewer barriers to adherence. For many people with early to moderate disease, SLT can be used first, with drops added later only if needed. This article explains how SLT works, what results to expect, who benefits most, and how to think through the trade-offs—plus practical FAQs you can use at your next visit.

Essential Insights

  • SLT can lower eye pressure comparably to first-line drops for many people, often reducing or delaying the need for daily medication.
  • The strongest advantage of SLT is consistency: it removes day-to-day dosing variability that can undermine long-term pressure control.
  • The effect can wear off over time, and not everyone responds; follow-up testing remains essential even when pressure looks “good.”
  • Most people return to normal activities quickly, but you should plan for a short recovery window and a pressure check soon after treatment.

Table of Contents

What makes SLT first-line now

SLT is not “new,” but how clinicians think about first-line therapy has changed. The modern goal is not only to lower intraocular pressure (IOP) once, but to keep it controlled reliably over years—while preserving quality of life and minimizing treatment friction.

The biggest practical difference between SLT and drops is adherence. Eye drops can work very well when taken correctly, but real life gets in the way: busy mornings, travel, arthritis, tremor, cognitive load, and simple “treatment fatigue.” Even small patterns of missed dosing can lead to higher average IOP and more fluctuation—both of which can matter for long-term optic nerve health. SLT shifts the work from the patient’s daily routine to a one-time (or occasional) office procedure.

SLT also fits the “stepwise” approach many people prefer. Starting with SLT can mean:

  • No daily medication at the beginning, or fewer medications overall.
  • Fewer preservative-related surface symptoms (dryness, burning, redness) that can build over time.
  • A clearer sense of what your baseline disease looks like before layering multiple therapies.

Long-term control is the other reason SLT has moved earlier. Many patients do not need maximal pressure lowering on day one. Instead, they need steady IOP reduction that matches their disease stage, risk factors, and rate of change on visual field and imaging tests. SLT can be a strong first step for mild to moderate open-angle disease, with drops added later if the target IOP is not reached or if the effect fades.

There is also a systems-level shift. Clinics increasingly focus on treatments that reduce ongoing medication burden and simplify follow-up. From the patient’s perspective, that can translate into fewer pharmacy trips, fewer prescription changes, and fewer decisions each day about timing and technique.

The bottom line: SLT is often considered first-line now because it can deliver meaningful pressure reduction with fewer daily barriers—while keeping future options wide open if more treatment is needed later.

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Who is a good candidate for SLT

SLT is designed for eyes where the drainage angle is open and visible, allowing the laser to treat the trabecular meshwork—the tissue that regulates outflow of the eye’s fluid. Most candidacy decisions come down to diagnosis type, angle anatomy, disease stage, and practical needs.

Diagnoses that commonly fit SLT first

  • Ocular hypertension (higher IOP without clear optic nerve damage): SLT can be a practical way to lower pressure early without committing to lifelong drops immediately.
  • Primary open-angle glaucoma (early to moderate): SLT is often appropriate when the goal is steady pressure reduction with minimal medication burden.
  • Some secondary open-angle glaucomas: Depending on the cause and angle status, SLT may still be helpful, but the expected response can differ.

People who often benefit most

SLT tends to be especially appealing if any of these apply:

  • You struggle with drops (side effects, cost, dosing complexity, dexterity, or memory).
  • You have ocular surface irritation or dryness that could worsen with long-term preserved drops.
  • You want to reduce medication load because you already manage multiple chronic medications.
  • You prefer a “procedure-first” approach when appropriate and safe.

When SLT may be less ideal as the first move

SLT is not one-size-fits-all. Your clinician may steer you toward drops or other options first if:

  • Glaucoma is advanced and a larger or faster pressure reduction is needed.
  • The angle is not sufficiently open, or the trabecular meshwork is difficult to visualize.
  • You have active inflammation in the eye or certain unstable corneal or uveitic conditions.
  • Your pressure is already near target, and the incremental benefit is likely to be small.

A practical “fit” checklist for your visit

Consider asking:

  • Is my glaucoma mild, moderate, or advanced based on the optic nerve and visual field?
  • What is my target IOP, and how far am I from it?
  • Do you expect SLT alone to reach that target, or would drops likely still be needed?

A good candidate is not just an eye with an open angle—it is a person whose disease goals and day-to-day realities match what SLT does best: dependable pressure lowering with less daily treatment complexity.

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How SLT is done and what to expect

SLT is an outpatient, in-office laser procedure that usually takes only minutes per eye. The visit itself is longer because of preparation and post-laser pressure checks, but the laser time is brief.

Before the laser

You will typically have:

  • A full eye exam and gonioscopy (a lens-based exam to confirm the angle is open and treatable).
  • Numbing drops so the procedure is comfortable.
  • Sometimes a pre-treatment drop to reduce the chance of a short-term pressure spike.

You may be asked to avoid driving yourself, especially if both eyes will be treated the same day, because vision can be temporarily blurry from drops and the contact lens used during treatment.

During the procedure

  • A special contact lens is placed on the eye to focus the laser.
  • You look at a fixation light while the clinician delivers a series of laser spots around the drainage tissue.
  • Many people feel little to no pain—often just mild pressure from the lens and occasional brief sensation during laser spots.

It is normal to see bright flashes or feel momentary awareness, but the goal is a calm, steady experience rather than something “intense.”

Right after the laser

Common immediate experiences include:

  • Mild redness or irritation
  • Light sensitivity
  • Slightly blurred vision for a few hours

Most clinics check IOP shortly after the procedure and may prescribe short-term anti-inflammatory drops (the exact approach varies). You will be given clear instructions about whether to continue any existing glaucoma drops.

Recovery timeline

  • Same day: You can usually return to routine activities, but expect mild irritation.
  • First week: The pressure-lowering effect may begin, but it often strengthens over several weeks.
  • Weeks 4–8: This is a common window for assessing the full effect and adjusting the treatment plan.

If you wear contact lenses, ask when you can resume. If you have a physically demanding job, confirm whether a short pause is recommended.

The key expectation to hold: SLT is quick, but it is not instant. The result is typically evaluated over weeks with follow-up IOP checks and, over time, optic nerve monitoring.

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Expected pressure drop and success rates

A helpful way to think about SLT is that it aims for meaningful, clinically useful pressure reduction, not perfection. The “right” result depends on where you start and what your target IOP is.

How much can SLT lower IOP?

In many patients with ocular hypertension or open-angle glaucoma, SLT produces a moderate drop in IOP that can be similar to what you might expect from a first-line drop. The response is often stronger when:

  • Starting IOP is higher
  • The drainage tissue is clearly visible and treatable
  • Disease is early and the system is less “treatment exhausted” by years of therapy

Some people achieve drop-free control after SLT, while others still need one medication to reach target. A smaller group does not respond enough to count as a success, even when the procedure is performed correctly.

Why results vary

SLT does not “open a blocked pipe” in the simple mechanical sense. It influences the drainage system’s function and biology, so the response depends on factors like:

  • Individual tissue behavior and healing response
  • Baseline outflow resistance
  • The severity and subtype of glaucoma
  • Coexisting ocular surface or inflammatory tendencies

What success looks like clinically

Clinicians often define success using a mix of:

  • Percentage reduction from baseline IOP
  • Achieving a pre-set target IOP
  • Stability on visual field and optic nerve imaging over time
  • Reduced need for additional drops or procedures

From a patient standpoint, success can also mean fewer side effects, fewer refills, and less daily stress around medication timing.

Does SLT help beyond pressure?

The primary purpose is IOP lowering. However, by reducing dependence on daily drops (and preservatives), SLT can indirectly help comfort and adherence—both of which support long-term management.

The most realistic expectation is this: SLT often provides a strong first step and can meaningfully reduce treatment burden, but it still requires follow-up and may be part of a longer plan that includes drops or additional procedures later if your target changes.

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Follow-up, repeat SLT, and next steps

Glaucoma care is a long game. SLT can be an excellent opening move, but the plan must include follow-up because pressure response and disease stability are not the same thing.

Typical follow-up schedule

Exact timing varies, but many care plans include:

  1. Early pressure check soon after treatment (to detect short-term spikes).
  2. One or more visits over the next 4–8 weeks to measure the full effect.
  3. Ongoing monitoring (visual field testing, optic nerve imaging, and pressure checks) on a schedule matched to your risk and stage.

If you had SLT as first-line therapy, your clinician may re-check baseline tests after the pressure has stabilized to better judge your personal rate of change.

How long does SLT last?

SLT can last years in some people, but it often diminishes over time. That does not mean it “failed”; it means the drainage system has gradually returned toward its prior behavior. The key is catching that change early with routine monitoring.

Can SLT be repeated?

In many cases, yes. Repeat SLT can be considered when:

  • The first treatment worked but the effect faded
  • You need a further pressure reduction and want to avoid adding more drops
  • The angle remains open and treatable

Repeat results can be good, but they may be less robust than the first treatment for some patients. The decision to repeat is usually based on your IOP trend, optic nerve status, and how close you are to target.

What if SLT is not enough?

If the pressure reduction is smaller than needed, next steps often follow a logical ladder:

  • Add or adjust topical medication (often starting with one agent)
  • Consider another laser session if appropriate
  • Discuss other procedures if disease stage or progression warrants stronger intervention

A useful mindset: SLT does not “use up” your future options. Whether it works wonderfully or only partially, it can still provide value—either by reducing medication load or by clarifying how aggressive your disease is and how low your target IOP truly needs to be.

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Side effects, risks, and safety caveats

SLT has a strong safety record, but “low risk” is not “no risk.” Understanding the realistic downsides helps you plan and spot problems early.

Common, usually mild effects

Many people have temporary symptoms that resolve within hours to a few days:

  • Redness or gritty sensation
  • Light sensitivity
  • Mild aching or pressure-like feeling
  • Brief blurred vision from drops or the contact lens

These are typically managed with short-term drops (when prescribed) and simple comfort measures.

Short-term pressure spikes

A key safety point is the possibility of an IOP spike shortly after treatment. This is why clinics often:

  • Use preventive drops in selected patients
  • Recheck IOP after the procedure or soon afterward
  • Schedule close early follow-up

Most spikes are temporary and treatable, but they matter more in advanced glaucoma where the optic nerve has less reserve.

Inflammation and rare complications

Some eyes develop more noticeable inflammation, which may require additional anti-inflammatory treatment. Rarely, patients can experience:

  • Persistent pressure elevation requiring added therapy
  • Corneal surface irritation that takes longer to settle
  • Worsening glare or halos temporarily (often related to surface irritation or dryness)

Serious, vision-threatening complications are uncommon, but you should treat any sudden change seriously.

When to call urgently

Contact your eye clinic promptly if you develop:

  • Significant pain not improving over several hours
  • Sudden drop in vision
  • Nausea with eye pain (possible high-pressure episode)
  • Marked redness with discharge

Important limitation to keep in mind

SLT treats pressure, not the optic nerve damage already present. Even if IOP improves, you still need scheduled testing to confirm stability. Some people progress at “normal” pressures, and targets may need adjustment over time.

Overall, SLT is widely used because the risk profile is favorable and the procedure is brief. The safest outcomes come from pairing SLT with the right follow-up plan and clear instructions about what symptoms should trigger a call.

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FAQs for patients and caregivers

Will I still need drops after SLT?

Maybe. Some people stay off drops for a meaningful period; others still need one medication to reach target. The goal is not always “no drops,” but the simplest plan that keeps your optic nerve stable.

Is SLT painful?

Most patients describe SLT as more strange than painful. Numbing drops help, and the contact lens sensation is often the most noticeable part. If you are sensitive or anxious, tell your clinician—small adjustments can make the experience easier.

How soon will my pressure go down?

Some effect can appear early, but many clinicians judge the full result over several weeks. Expect a follow-up plan that measures IOP more than once before deciding whether it “worked enough.”

Can SLT be done in both eyes?

Often yes—sometimes on the same day, sometimes on separate visits. The choice depends on your risk of pressure spikes, your disease severity, clinic protocol, and personal preference.

Does SLT replace surgery?

SLT is not the same as incisional glaucoma surgery. For early or moderate disease, it may delay or reduce the chance of needing stronger interventions. For advanced or rapidly progressing glaucoma, SLT may be only one part of a larger plan.

What should I ask at my SLT consultation?

Bring these questions:

  • What is my target IOP, and what target are we aiming for after SLT?
  • What is the plan if SLT only partially lowers pressure?
  • Will I use anti-inflammatory drops afterward, and for how long?
  • When is my pressure check, and what symptoms should trigger an urgent call?
  • How will we measure success—pressure alone, or pressure plus visual field and imaging stability?

If I have dry eye, is SLT better than drops?

It can be. Long-term drops—especially preserved drops—may worsen surface irritation in some people. SLT can reduce drop exposure, but you may still need drops later, so a dry-eye plan is still valuable.

How do I decide between SLT and starting a prostaglandin drop?

A practical decision framework:

  • Choose SLT-first if you want to minimize daily treatment burden, you have adherence concerns, or you have surface sensitivity.
  • Choose drops-first if you need an immediate predictable approach, SLT access is limited, or your clinician believes your anatomy or stage makes a stronger early medication plan more suitable.
  • Choose a combined strategy when you need more reduction than either alone is likely to deliver, or when you want SLT to reduce the number of drops needed long-term.

The best choice is the one that fits your target IOP, your eye’s anatomy, and what you can realistically maintain for years—not just weeks.

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References

Disclaimer

This article is for general education and cannot diagnose glaucoma, determine your target eye pressure, or replace care from an eye professional. Glaucoma management is individualized and depends on your optic nerve findings, visual field results, eye anatomy, overall health, and risk of progression. If you have sudden vision changes, significant eye pain, nausea with eye pain, or rapidly worsening redness after any eye procedure, seek urgent medical attention or contact your eye clinic immediately.

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