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Editors Selection IGR 16-3
Surgical treatment: Laser trabeculoplasty
Comment by Karim Damji & Lisa Heckler on:
59573 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: 206-212
This first-of-its-kind RCT compared the efficacy of SLT with a prostaglandin analog (PGA) travaprost in patients with primary angle closure (PAC) or PAC glaucoma (PACG) who have undergone previous laser iridotomy and in whom the trabecular meshwork was visible for at least 180°.1 This is an important question given the burden of PAC associated blindness globally, and difficulties with cost, adherence and toxicity related to glaucoma medications. A previous study by Ho also looked at SLT in PACG patients and was prospective but not controlled.2
In this well-powered three-center unblinded study, 50 patients were randomized to SLT and 50 to medication. SLT included pre-treatment with brimonidine and pilocarpine, and post-treatment with prednisolone. Analysis was based on intent to treat. At six months, there was excellent follow-up and no differences between the SLT and PGA arms in IOP reduction (4.0 vs. 4.2 mmHg or 16.9% vs. 18.5% respectively). More patients in the PGA group achieved IOP ≤ 21 mmHg without additional medications vs. the SLT group (84% vs. 60%). In the SLT group one patient had an IOP spike and no patients developed additional PAS; in the PGA group one patient had allergic conjunctivitis and another uveitis. A 4.8% decrease in endothelial cell count (ECC) was noted in the SLT arm vs. a mean increase of 0.4% in the medication arm.
The authors excluded secondary causes of angle closure but do not mention exfoliation syndrome, which can result in a combined mechanism glaucoma in some patients. SLT was repeated at the one- or three-month follow-up if there was less than 20% reduction in IOP; this may have been premature given that it can take two to four months for the full effect of SLT after treatment.3,4
This study provides convincing evidence that at six months SLT is as effective as a PGA in treating high IOP in PAC patients after iridotomy, albeit with a 5% decline in ECC. Longer follow-up and further study will be needed to better elucidate its role in this patient population.
References
- Narayanaswamy A, Leung CK, Istiantoro DV, et al. Efficacy of selective laser trabeculoplasty in primary angle-closure glaucoma: a randomized clinical trial. JAMA Ophthalmol 2015;133(2):206-212.
- Ho CL, Lai JS, Aquino MV, et al. Selective laser trabeculoplasty for primary angle closure with persistently elevated intraocular pressure after iridotomy. J Glaucoma 2009;18(7):563-566.
- Latina MA, Sibayan SA, Shin DH, Noecker RJ, Marcellino G. Q-switched 532-nm Nd:YAG laser trabeculoplasty (selective laser trabeculoplasty): a multicenter, pilot, clinical study. Ophthalmology 1998;105(11):2082-2088; discussion 2089-2090.
- Nagar M, Luhishi E, Shah N. Intraocular pressure control and fluctuation: the effect of treatment with selective laser trabeculoplasty. Br J Ophthalmol 2009;93(4):497-501.
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