Incidence of Serious Complications After SLT Less Than 0.1%

With myopia a contributing factor to hyperopic shift and corneal scarring, the authors suggest that clinicians should avoid targeting blood vessels in the anterior chamber angle and consider using lower energy settings when treating high myopic patients. Pictured here is hyphema in the angle during an SLT procedure.  Photo: Nate Lighthizer, OD. Click image to enlarge. Selective laser trabeculoplasty (SLT) has been shown to be a safe and effective treatment for glaucoma, with many now considering it a first-line treatment, including the European Glaucoma Society. While there are some mild adverse events after the procedure, little is known about the incidence of serious complications. Finnish researchers investigated this and found that the number of troubling complications was low, with only one case of permanent vision deterioration in more than six thousand procedures. The findings were reported in Acta Ophthalmologica.A total of 6,081 SLTs (4,601 eyes) of 2,812 patients from the Helsinki University Hospital were analyzed. The primary outcome measures were serious complications, including corneal edema, corneal scarring, hyperopic shift, synechia, anterior chamber bleeding and hyphema.Twelve patients had bleeding in the anterior chamber angle and four of them developed hyphema. All four patients with hyphema were on antiplatelet or anticoagulation treatment. “More interestingly, if bleeding occurred while on antiplatelet treatment (aspirin), it led to hyphema in all four cases,” the authors wrote in their Acta Ophthalmologica paper. “Three patients with bleeding treated with direct Xa inhibitors [a form of anticoagulant] did not develop hyphema. This might suggest that if bleeding from the anterior chamber angle or trabecular meshwork occurs, it tends to be more severe in patients on antiplatelet therapy compared to those on direct factor Xa inhibitors or no anticoagulation therapy.”Corneal edema or Descemet’s membrane folds were reported in six treated eyes. One myopic eye had a permanent corneal scarring, thinning and irregular astigmatism with a hyperopic shift (5.3D with recovery to 1.25D in three years), resulting in poor visual acuity. The incidence was less than 0.2/1,000 for all SLT treatments and 1/648 for SLT laser treatments in high myopia  (SE ≤ -5.00D).Previous studies detailing patients with corneal edema, haze and thinning noted that at-risk subjects were highly myopic (SE between -5.00 and -20) before treatment and developed a hyperopic shift in their refraction. This implicates myopia as a contributing factor to hyperopic shift and corneal scarring, the authors wrote.There was one hyperopic shift with irregular astigmatism and corneal thinning. The complication occurred in an eye with myopia of SE -5.25D. The eye recovered from the first SLT with low energy (0.3mJ). “Still, the second SLT with higher energy (1.0mJ) caused permanent alterations in the cornea, suggesting that higher energy combined with high myopia could contribute to corneal damage,” the authors explained in their article.Another recent study, regarding energy settings on the laser, showed that higher energy—cavitation bubbles in 50% to 75% of the laser spots—is more efficient than lower energy that’s just below the cavitation bubble threshold. Taking this into consideration, the authors of the present study suggest that avoiding high SLT energy levels with frequent bubble formation may be preferable in patients with high myopia.With the prevalence of high myopia estimated to increase significantly globally, the authors explained that there may be an increase in glaucoma diagnoses and SLT treatments for high myopia patients, which could lead to an increase in the number of rare SLT complications. Even with this potential increase, the authors concluded that these findings may help clinicians reassure patients about SLT safety when offering SLT as a first-line treatment for ocular hypertension or open-angle glaucoma.Click here for the journal source. Ojanen ES, Turunen JA, Harju M. The incidence of serious complications after selective laser trabeculoplasty. Acta Ophthalmologica. June 1, 2025. [Epub ahead of print.]