- What is SLT Laser?
- SLT Laser — Procedure
- SLT Laser — Glaucoma
- SLT Laser — Eye Pressure Reduction
- SLT Laser — Side Effects
- SLT Laser — NHS Guide
What is SLT Laser?
Selective Laser Trabeculoplasty, commonly called SLT laser, is a minimally invasive eye treatment used to lower intraocular pressure (IOP) in people with open-angle glaucoma or ocular hypertension. It uses very short, low-energy pulses of light that specifically target pigmented cells within the trabecular meshwork—the eye’s natural drainage tissue—without damaging surrounding structures. Because the laser is “selective,” the energy is absorbed only by certain cells, which initiates a gentle biological response that improves fluid outflow. Unlike older thermal lasers, SLT does not scar or shrink tissue; instead, it nudges the drainage system to work better. The treatment is performed in a clinic setting, usually takes only a few minutes per eye, and requires no incisions or stitches. For many patients, SLT reduces the need for daily pressure-lowering eye drops, or it can be combined with drops to achieve safer target pressures. It is repeatable over time and preserves future options, including medications, minimally invasive glaucoma surgery (MIGS), or filtering surgery, if needed.
Patients often ask how SLT fits into a long-term glaucoma care plan. A simple way to think about it is that SLT is one tool in a layered approach to protecting the optic nerve, similar to how high blood pressure is treated with lifestyle, medication, and procedures as needed. After a full eye exam and pressure check, your clinician may recommend SLT if your pressures are above target, if drop side effects or cost are problematic, or if adherence is challenging. The actual visit is straightforward: topical anesthetic drops are used, a contact lens is placed to focus the laser, and the doctor applies a series of pulses around the drainage angle. Vision is typically unaffected immediately afterward, though mild blur or light sensitivity can occur for a short time. Follow-up checks ensure that pressure is trending down over the next weeks. Because SLT leverages your eye’s natural pathways rather than creating a new drainage route, it offers a safe, evidence-based way to lower pressure with minimal disruption to daily life.
SLT Laser — Procedure
Understanding the SLT laser procedure step by step helps reduce anxiety and sets realistic expectations. On the day of treatment, you arrive with or without a driver (many people can drive afterward, but follow your clinic’s advice). The staff confirms your medications and may check your pressure before starting. Numbing drops are placed to keep the eye comfortable. Your doctor then positions a special gonio lens on the eye to visualize the trabecular meshwork, the circular drainage tissue at the front of the eye. Using the laser, the doctor delivers a ring of gentle pulses—often 50 to 100 shots—over part or all of the drainage angle. You may see brief flashes of green light and feel a light tapping sensation, but pain is uncommon. The laser energy is low and designed to target pigmented cells, triggering a cellular response that improves outflow rather than burning tissue. The treatment typically takes 5–10 minutes per eye.
Immediately after SLT, the lens is removed and the eye is rinsed. Your pressure may be rechecked 30–60 minutes later. Some clinicians prescribe a short course of anti-inflammatory drops; others prefer watchful waiting because SLT relies on a controlled inflammatory signal to work. It is normal to experience mild scratchiness, redness, or light sensitivity for a day or two. Most people resume normal activities the same day. Pressure reduction does not occur instantly; the effect builds gradually over 2–6 weeks as the trabecular meshwork responds and fluid outflow increases. Your follow-up plan typically includes one visit in the first few weeks and another at 6–12 weeks to judge the full effect. If adequate lowering is achieved, your doctor may reduce the number of drops. If the response is partial, SLT can be repeated or combined with medication. Because SLT does not scar the drainage tissue, repeat treatments remain an option, and the procedure does not “burn bridges” for future MIGS or filtering surgeries should they become necessary later on.
SLT Laser — Glaucoma
Glaucoma is a group of diseases that damage the optic nerve, usually associated with elevated eye pressure, and it is a leading cause of irreversible vision loss worldwide. In open-angle glaucoma, the drainage angle looks open, but fluid exits too slowly, allowing pressure to rise. SLT laser directly addresses this outflow problem by enhancing the function of the trabecular meshwork. For newly diagnosed patients, SLT is increasingly considered as a first-line therapy, particularly when daily drops are impractical, cause side effects, or do not sufficiently lower pressure. For patients already on drops, SLT can reduce the number of medications required to reach target pressure, which may improve quality of life, reduce costs, and minimize ocular surface irritation. Clinical studies show that many individuals achieve meaningful pressure reductions, and some maintain control for years before needing a retreatment or medication adjustment.
Beyond pressure numbers, the broader glaucoma care plan remains essential. Regular visual field testing, optic nerve imaging, and pressure monitoring help track disease stability. Lifestyle matters too: adherence to follow-up, safe use of any prescribed drops, and awareness of systemic medications that may influence eye pressure (for example, chronic steroid use) all play roles. SLT is not a cure and does not reverse existing optic nerve damage, but by lowering pressure, it reduces the risk of future loss. It also integrates well with other modern options such as MIGS at the time of cataract surgery. For people with pigmentary glaucoma or ocular hypertension, SLT may be particularly effective because the target tissue contains more pigment, which absorbs laser energy efficiently. Your doctor will tailor recommendations based on baseline pressure, optic nerve status, visual field findings, age, and personal preferences, with the shared goal of preserving vision over a lifetime.
SLT Laser — Eye Pressure Reduction
Eye pressure, or intraocular pressure (IOP), results from the balance between fluid produced inside the eye and fluid leaving through drainage pathways, primarily the trabecular meshwork. SLT laser lowers IOP by improving this outflow, often achieving reductions in the 20–30% range in suitable patients. The response is individualized: some people experience larger drops, others more modest changes. The effect is not immediate because SLT sets off cellular signals that remodel and enhance drainage over weeks. Importantly, SLT does not preclude other pressure-lowering strategies—many care plans combine SLT with one or two drops, or add a minimally invasive glaucoma procedure if additional reduction is needed. Your provider will define a target pressure based on disease severity; for example, someone with early glaucoma may aim for low- to mid-teens, while advanced disease may require even lower targets to protect the optic nerve.
Monitoring outcomes after SLT focuses on both the number and the trend of your pressure readings. A single measurement can fluctuate with time of day, stress, or technique, so repeated checks matter. If your pressures fall close to target and remain stable, you may be able to taper drops under guidance. If the benefit fades after months or years, SLT can often be repeated because it does not scar the meshwork. When combined with healthy habits—consistent follow-ups, correct drop instillation if prescribed, and managing systemic health conditions—SLT provides a durable platform for long-term control. Remember that symptoms are not a reliable indicator; glaucoma is typically silent until late stages. Even if you feel fine, keeping pressures at target protects the optic nerve and supports stable visual fields, which is the ultimate goal of treatment.
SLT Laser — Side Effects
All medical procedures carry some risk, and SLT laser is no exception, though it has a strong safety profile. The most common side effects are mild and temporary: slight redness, a sandy or scratchy sensation, transient blur, or light sensitivity in the first 24–48 hours. A small pressure spike can occur shortly after treatment; your doctor may check your IOP within an hour and can treat any rise with drops if needed. Mild inflammation is part of the intended biological response and usually subsides without issue; some clinicians prescribe a short anti-inflammatory course to keep symptoms comfortable. Rarely, patients report headache or aching around the treated eye, which typically responds to over-the-counter pain relievers if appropriate for you. Infection and serious complications are exceedingly uncommon because SLT is non-incisional and quick.
Knowing when to call your clinic is important. Seek advice if you experience persistent pain, a sudden drop in vision, halos with eye pain, or symptoms that worsen after the first day. People with very advanced glaucoma may need closer monitoring in the immediate post-procedure period because even brief pressure fluctuations can be risky for a fragile optic nerve. If you use contact lenses, you may be advised to pause wear for a short time. Medication allergies, prior surgeries, or unique anatomy do not automatically disqualify you from SLT, but they should be discussed at evaluation. Overall, the balance of benefits and risks strongly favors SLT for many patients: it avoids daily medication burden, preserves future options, and has a safety record that makes it a dependable first- or second-line therapy in modern glaucoma care.
SLT Laser — NHS Guide
For readers in the United Kingdom, SLT laser is widely available through NHS hospital eye services for open-angle glaucoma and ocular hypertension. Many NHS clinics now consider SLT as an initial treatment option, reflecting evidence that it safely lowers pressure and can reduce reliance on long-term drops. Access usually begins with a referral from your optometrist or GP to a hospital eye clinic, where a glaucoma specialist performs a comprehensive assessment, including pressure measurement, optic nerve evaluation, visual fields, and gonioscopy (to view the drainage angle). If SLT is appropriate, the team will explain the procedure, consent, and aftercare. The treatment is delivered in an outpatient laser suite, and you can generally go home shortly afterward. Follow-up appointments are scheduled to assess pressure response over the next weeks and to adjust any medications accordingly, aiming for a personalized target pressure based on your disease stage and risk factors.
The NHS pathway emphasizes consistency, education, and shared decision-making. You will receive guidance on what to expect the day of treatment, how to use any prescribed drops, and when to seek help if symptoms occur. Because SLT is repeatable and cost-effective, it aligns well with NHS goals of high-quality, sustainable care. If you also have cataracts, your team may discuss combining pressure-lowering strategies—such as performing MIGS at the time of cataract surgery—while maintaining SLT as a future option. Patients often appreciate that SLT reduces the daily burden of drops, which can be difficult to maintain over years and may irritate the ocular surface. Whether SLT is used alone or alongside medications, your hospital eye service will continue monitoring optic nerve structure and function at regular intervals to ensure that vision remains stable. If pressures rise later, options include repeat SLT, medication adjustments, or surgical pathways, all within the same coordinated NHS framework.
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