Effectiveness of Selective Laser Trabeculoplasty in Open Angle Glaucoma
Selective laser trabeculoplasty is highly effective for treating open angle glaucoma, achieving IOP reduction comparable to prostaglandin analog medications and superior to older beta-blocker therapy, with the added advantages of better safety profile and potential repeatability compared to argon laser trabeculoplasty. 1
IOP Reduction Efficacy
SLT demonstrates clinically significant IOP lowering across multiple studies:
SLT achieves comparable IOP reduction to prostaglandin analogs (the current gold-standard medical therapy), though one prospective study found SLT was only equivalent to latanoprost when 360 degrees of trabecular meshwork was treated, with latanoprost showing better IOP-lowering effect at 90 and 180 degrees of treatment 1
A multicenter randomized trial comparing SLT to medical therapy as initial treatment showed similar IOP reduction after 1 year of follow-up 1
Meta-analysis of 5 studies with 366 participants confirmed that SLT and topical medication demonstrate similar success rates and effectiveness in lowering IOP 1
In prospective studies, SLT as initial treatment achieved average IOP reductions of 8.3 mmHg (31.0%), with responder rates (≥20% IOP reduction) of 83% 2
Over 2-year follow-up, SLT decreased IOP by a mean of 17.2% (3.3 mmHg), though survival analysis showed only 48% of eyes maintained >3 mmHg reduction and 41% maintained >20% reduction at 2 years 3
Comparison to Argon Laser Trabeculoplasty
SLT is non-inferior to ALT with important advantages:
Multiple prospective and retrospective studies indicate SLT appears comparable to but not better than ALT in lowering IOP 1
Meta-analysis of randomized controlled trials confirms SLT is non-inferior to ALT in IOP reduction and achieving treatment success 1
SLT produces less thermal damage to the trabecular meshwork compared to ALT due to selective absorption by pigmented cells using lower energy 1
SLT has a better safety profile with less ocular discomfort compared to ALT 1
Repeatability and Long-Term Outcomes
SLT offers potential advantages for repeat treatment:
While controlled randomized trials have not definitively demonstrated superior success with repeated SLT treatments, retrospective studies show similar IOP reduction and success rates with repeat SLT compared to initial SLT 1
This contrasts with repeat ALT, which has low long-term success rates with failure occurring in nearly 90% of eyes by 2 years 1
The lack of coagulation damage to trabecular meshwork makes SLT potentially repeatable, unlike ALT which causes structural damage 4, 5
More robust evidence is needed to determine efficacy as a repeated procedure 1
Safety Profile
SLT demonstrates favorable safety characteristics:
Mild anterior chamber inflammation after treatment is the most common side effect 1
IOP spikes occur in 4.5% to 27% of eyes, similar to rates observed with ALT 1
Eyes with more heavily pigmented trabecular meshwork are more prone to IOP spikes 1
Overall perioperative treatment is well tolerated and safe 1
Clinical Positioning and Indications
Current guideline recommendations position SLT strategically:
Laser trabeculoplasty can be considered as initial therapy in selected patients or as an alternative for patients at high risk for nonadherence to medical therapy 1
Specific indications include patients who cannot or will not use medications reliably due to cost, memory problems, difficulty with instillation, or intolerance to medication 1
SLT can be used across multiple glaucoma subtypes including primary open-angle glaucoma, pseudoexfoliation glaucoma, pigmentary glaucoma, normal-tension glaucoma, ocular hypertension, and juvenile glaucoma 5
Greatest IOP decrease occurs in treatment-naïve eyes and those with pseudoexfoliation glaucoma 3
Treatment Parameters
Optimal treatment approach:
360-degree treatment appears more effective than partial treatment when comparing to prostaglandin analogs 1
Treatment can be performed to 180 degrees or 360 degrees depending on clinical scenario 1
SLT efficacy is independent of angle pigmentation in most studies 2
Medication Reduction Potential
SLT enables significant reduction in topical therapy:
In medically controlled glaucoma, SLT enabled medication reduction in 97% of eyes at 6 months and 87% at 12 months 6
Mean medication reduction was 2.0 medications at 6 months and 1.5 medications at 12 months while maintaining target IOP 6
However, SLT cannot totally replace topical glaucoma treatment in most cases 3
Important Caveats
Key clinical considerations:
While effective, 30% to more than 50% of eyes may require additional surgical treatment within 5 years, based on historical laser trabeculoplasty data 1
Patient selection should be optimized to improve cost-effectiveness ratio 3
SLT does not interfere with success of future incisional surgery, making it a safe intermediate option 4, 5
Perioperative medications (brimonidine, apraclonidine) are superior to placebo in preventing IOP spikes during the first 24 hours after laser trabeculoplasty 1