SLT vs. topical treatment with prostaglandin analogues in the management of PACG
Reviewed by Lona Jawaheer

Selective laser trabeculoplasty (SLT) has been shown to be useful in the management of primary open angle glaucoma (POAG), but its use in primary angle closure (PAC) / primary angle closure glaucoma (PACG) has yet to be validated. Narayanaswamy et al. present the results of a randomised controlled study involving 100 patients with PAC / PACG having previously undergone laser peripheral iridotomies with subsequent opening of at least 180º of the angles. Fifty participants were randomly allocated to treatment with a topical prostaglandin analogue (PGA) and 50 to treatment with SLT in order to address baseline intraocular pressures (IOP) above 21mmHg. The results after a six month period of follow-up showed a decrease in IOP of 4.0mmHg with SLT vs. 4.2mmHg with PGA (p=0.78), and a percentage decrease in IOP of 16.9% with SLT vs. 18.5% with PGA (0.52). Following treatment, 60.0% of SLT patients had IOPs lower than 21mmHg without medications, compared to 84.0% of PGA patients (p=0.08). And 28.6% of patients receiving SLT were treated repeatedly, to address a reduction in IOP of less than 20%. Side-effects of SLT included a transient post-treatment IOP spike of greater than 5mmHg in one patient (2%), and a significant decrease of 4.8% in mean endothelial cell count (p=0.01). The authors also note the difficulty in performing 360º SLT (known to have the best IOP-lowering effect) owing to the anatomy in PAC / PACG. Side-effects of treatment with PGA included uveitis and allergic uveitis (4%) leading to interruption of treatment. This study shows that SLT does produce a decrease in IOP in patients with PAC / PACG which is comparable to that obtained with a PGA. Treatment with SLT in PAC / PACG presents the advantage of avoiding a long-term treatment with its associated cost, risk of non-compliance and its side-effects. However, a longer follow-up period is required to ascertain the long-term effects of SLT. 

Efficacy of selective laser trabeculoplasty in primary angle-closure glaucoma. A randomized clinical trial.
Narayanaswamy A, Leung CK, Istiantoro DV, et al.
JAMA OPHTHALMOLOGY
2015;133(2):206-12.