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Selective laser trabeculoplasty (SLT) is controversially discussed as first-line therapy in glaucoma patients. Its use has experienced numerous ups and downs, depending on geography, reimbursement rates, and other factors. With the introduction of alternative technologies (e.g., pattern scanning laser and micropulse trabeculoplasty) laser therapy is attracting increasing interest.
Lee et al. investigated the determinants of succes after SLT in a Chinese population from Hong Kong. Patients received bilateral 360° SLT in the same session. This study is of interest for several reasons. First, little data is available on SLT efficacy in Chinese populations. Second, nearly half of patients had normal tension (NTG) glaucoma.
The effect of SLT on NTG has not been widely studied. The authors reported a success rate of 53% (e.g., IOP-lowering of ≥ 20 mmHg after one month), with a mean IOP-lowering of 19.8%. In successful eyes, IOP lowering was 32%, demonstrating SLT's usefulness in NTG eyes. This level of IOP reduction could label SLT a 'laser prostaglandin' under two caveats: It works in roughly one out of two eyes and with diminishing results over time.
Being able to better predict which eyes would respond might increase clinician's acceptability of SLT. This study shows that higher baseline IOP, thinner RNFL thickness, and use of topical cardbonic anhydrase inhibitors are associated with SLT success. This latter result is perplexing and the authors theorize that its is not so much the use of CAIs but rather the absence of prostaglandin eyedrops, in line with the presumed pro-inflammatory effects of SLT. This finding needs confirmation. A recent study did not find higher success in eyes without anti-inflammatory therapy after SLT.1 Limitations of the study are the short follow-up and absence of appropriate statistical analysis to account for the inclusion of both eyes of the same patients.2