Importance of patient selection
An important observation I have made while working with the SLT laser is that the results achievable are strongly influenced by disease. Patients at stages 1 and 2 of the disease seem to achieve better outcomes than those at later stages. Specifically, mean IOP reductions of 5.9 and 5.7 mm Hg were achieved among my patients with stage 1 and 2 glaucoma, respectively.
Of note, these levels of reduction were seen in more than 80% of patients. In comparison, SLT therapy was effective in no more than 50% of my stage 3 patients, resulting in a mean IOP reduction of only 4.7 mm Hg among this group at 1 to 3 months post-SLT.
Published literature, including a 2016 study by Schlote et al., support my observation that SLT outcomes are worse with advanced open angle glaucoma.4 This suggests that while such technology is exciting and offers favourable outcomes for glaucoma patients, it is important to recognise that such outcomes are not universal for all patients. Thus, it is vital that the treating physician selects patients for treatment appropriately.
In addition to disease stage, other factors, such as angle width and pigmentation level, influence both the outcomes obtainable with SLT and the technical settings that must be used when treating patients with the laser.
For example, in eyes with a higher degree of pigmentation, it is better to use a relatively low energy beam or apply treatment in several stages to minimise the risk of burns. In eyes with low levels of pigmentation, SLT is not really worthwhile as its ability to lower IOP in such eyes is minimal. Similarly, this treatment is typically ineffective in patients with pseudoexfoliation glaucoma.
As with any therapeutic intervention, while SLT laser offers great benefits and outcomes, it does carry a risk, albeit a low one, of side effects. My experience with the laser revealed just one case of IOP increase among a treatment group with more than 100 patients.
In this case, IOP rose to 35 mm Hg after SLT treatment. However, it dropped back to normal levels within 2 weeks (during which hypotensive eye drops were used to maintain IOP at acceptable levels). But as transient IOP rise has been widely reported after laser procedures, this is an observation that is not too unexpected.5