Gazzard et al. are to be congratulated on their well-designed landmark randomized-controlled study. The LiGHT trial provides insight into the safety, efficacy, cost-effectiveness, and impact on quality of life for initial selective laser trabeculoplasty (SLT) compared to initial medical therapy in treatment naive open-angle glaucoma and ocular hypertension patients.
The results show that 78% of eyes treated with initial SLT were controlled at 36 months. Patients in the SLT arm were at target intraocular pressure (IOP) for 93% of visits over three years compared with 91% of patients in the medication arm. Eleven eyes in the medication arm went on to require incisional glaucoma surgery while none of the patients in the SLT arm required surgery. No sight-threatening complications were reported in the SLT arm. The initial SLT approach resulted in significant cost savings per patient for the National Health Service (NHS). The primary outcome of the study was health-related quality of life, assessed using questionnaires. No significant differences in responses between the two arms were identified at 36 months.
These results corroborate what has been shown regarding safety and efficacy in previous, smaller studies comparing initial SLT to initial medical therapy.1,2 The LiGHT trial has the potential to shift early glaucoma management decision making toward SLT because of compliance, safety, and patient cost savings. However, caveats need to be considered for broader adoption of SLT.
While the cost-savings in initial treatment with SLT are an important benefit to consider, we should keep in mind that the results of a clinical trial run within the NHS in a hospital- based practice may not be generalizable to other health care systems or to individual private practice ophthalmologists who might not perform large volume glaucoma laser surgery.
Although SLT provides cost savings to the patient, it requires specialized equipment which comes at both large initial and maintenance costs to a clinical practice. Unlike YAG or diode lasers, SLT lasers cannot be used to perform other ocular procedures. Finally, the LiGHT trial's companion study showed that 25.9% of patients in the SLT arm underwent repeat SLT during the 36-month duration of the trial.3 Repeat treatment may have additional patient costs which were not captured in the initial study.
SLT is unlikely to have adequate treatment effect in patients requiring very low intraocular pressures
SLT requires specialized skill in examining the angle anatomy and knowing where to treat to achieve effect. Additionally, even in the best hands, SLT is unlikely to have adequate treatment effect in patients requiring very low intraocular pressures or those with normal-tension glaucoma because of intrinsic trabecular outflow resistance at mid-teens IOP.
Ultimately, most glaucoma specialists counsel their early glaucoma patients by offering both SLT and medical therapy and allowing the patient to choose their treatment. Patient perceptions of the invasiveness of laser therapy may affect broad adoption of SLT as a primary line treatment for glaucoma.