Direct Selective Laser Trabeculoplasty

( DSLT)

What are SLT and DSLT ?

SLT (Selective Laser Trabeculoplasty) and DSLT (Direct Selective Laser Trabeculoplasty) are laser treatments for glaucoma that reduce intraocular pressure.

Both use the same 532-nm wavelength laser. 

SLT requires manual application through a special contact lens (gonioscopy )  

DSLT is more automated, delivering laser energy directly to the eye without contact, making it faster and easier to have done.

History, ALT/SLT/DSLT Differences, NICE Guidelines

  • Laser trabeculoplasty first noted to reduce eye pressure in the 1970s. 

    In 1979, Wise and Witter popularised argon laser trabeculoplasty (ALT). 

    Selective laser trabeculoplasty (SLT) was introduced by Latina and Park in 1995. Since then, SLT has gained widespread adoption.

  • SLT uses a lower-energy Nd:YAG laser, causing minimal damage to the trabecular meshwork.

    ALT employs a higher-energy argon laser, producing thermal burns.

    SLT selectively targets pigmented cells with a larger spot size, is repeatable, and has fewer post-procedure complications.

    ALT affects all treated cells, is generally non-repeatable, and requires more precise application.

  • Selective Laser Trabeculoplasty (SLT) has success rate of approximately 70-80% in reducing intraocular pressure (IOP).

    Studies indicate that SLT can effectively delay or reduce the need for glaucoma medications. In a notable study published in the "Ophthalmology" journal, about 75% of patients experienced a 20% IOP reduction after SLT treatment.

    The procedure's effects generally last from one to five years, and it can be repeated if necessary. Compared to Argon Laser Trabeculoplasty (ALT), SLT is less invasive, with fewer complications, making it a preferred choice for many ophthalmologists and patients alike.

  • From 2022, NICE guidelines recommend offering selective laser trabeculoplasty (SLT) as first-line treatment for newly diagnosed ocular hypertension (OHT) with eye pressure over 24mmHg and for open-angle glaucoma (POAG) at any level of pressure. SLT is considered safer, more cost-effective, and potentially reduces the need for eye drops in managing glaucoma long-term.

    The update to the previous 2017 guidelines on glaucoma diagnosis and management (NG81) was made following the results of the Laser in Glaucoma and Ocular Hypertension (LiGHT) trial, which demonstrated the effectiveness and cost-efficiency of SLT compared to eye drops.

  • Direct selective laser trabeculoplasty (DSLT) presents several potential advantages over traditional selective laser trabeculoplasty (SLT) in glaucoma treatment.

    As a non-contact procedure, DSLT eliminates the need for a contact lens, making it more comfortable for patients and reducing the risk of infection.

    The treatment is more machine guided making it quicker and easier.

    DSLT is suitable for both open and closed angle glaucoma, expanding its applicability.

    Additionally, it is felt that,theoretically, it may result in fewer intraocular pressure spikes and less intraocular inflammation, potentially improving safety and patient outcomes.

  • The National Institute for Health and Care Excellence (NICE) has indeed recommended Selective Laser Therapy (SLT) as a first-line treatment for glaucoma and ocular hypertension (OHT). This recommendation is based on the findings of several studies, including the landmark Laser in Glaucoma and Ocular Hypertension (LiGHT) trial.

    Key Findings:

    1. SLT Efficacy: The LiGHT trial demonstrated that SLT is more effective than eye drops in controlling intraocular pressure (IOP) and reducing the progression of glaucoma. After six years, 69.8% SLT remained at their target IOP or lower without needing additional medication or surgery[2][4].

    2. Reduced Disease Progression: The study found that initial treatment with SLT resulted in statistically significant lower rates of disease progression and reduced need for glaucoma and cataract surgery compared to initial treatment with eye drops[2][4].

    3. Safety Profile: SLT has been shown to have a very good safety profile, with no sight-threatening complications. Intraocular pressure rose by more than 5 mmHg in only 1% of treated eyes, and other adverse events were comparable between the SLT and eye drop groups[2].

    4. NICE Guidance: The NICE guidance, updated in January 2022, recommends the use of SLT as a first-line treatment for OHT and chronic open-angle glaucoma (COAG), particularly for patients with an IOP of more than 24 mmHg and those at risk of visual impairment within their lifetime[1][5].

    5. International Recognition: The European Glaucoma Society and the American Academy of Ophthalmology have also updated their guidelines to include SLT as a first-line treatment option for OAG and OHT[2][4].

    Conclusion:

    The NICE recommendation for SLT as a first-line treatment for glaucoma and OHT is supported by robust evidence from the LiGHT trial and other studies. SLT has been shown to be effective, safe, and cost-effective, offering better long-term disease control and reduced need for surgical interventions compared to initial treatment with eye drops.

    Sources:

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