Wright and colleagues, in a post hoc analysis of visual field outcomes from the landmark Laser in Glaucoma and Ocular Hypertension Trial (LiGHT), have reported that rapid visual field (VF) progression is more common in patients treated with medications than in patients treated with selective laser trabeculoplasty (SLT) as primary therapy for openangle glaucoma or high-risk ocular hypertension. After excluding unreliable tests and eyes with short follow-up, 688 eyes (344 in each group) were analyzed. Trend-based changes in both total deviation (TD) and pattern deviation (PD) were modeled through up to six years of follow-up. Rapid progression was defined as a slope of > -1 dB/year, moderate progression between -0.5 and -1 dB/year, and slow progression less than -0.5 dB/year. The investigators reported that 26.2% of medically-treated eyes versus only 16.9% of SLT-treated eyes experienced moderate or rapid TD progression (relative risk 1.37, p < 0.001). In previous reports, the LiGHT team found that mean IOP reductions between groups were quite similar, which begs the question: why would SLT potentially reduce the rate of rapid VF progression better than medical therapy? The most obvious answer pertains to therapeutic adherence. Non-adherence with glaucoma medical therapy has been robustly characterized and is consistently suboptimal, while non-adherence with SLT is nil once the procedure has been performed.
Why is medical therapy still the preferred first-line treatment for most ophthalmologists
Self-reported adherence with medical therapy was high in LiGHT, but we are all familiar with patients who report adherence yet only use their medications around the time of office visits. These patients appear well-controlled when observed in the office but may be poorly controlled - and may progress - when non-adherent between visits. When one considers - as the investigators have - that adherence is higher in trials than in realworld use, the advantage of SLT over medical therapy in reducing the rate of VF progression as seen in LiGHT may be an underestimate of SLT's ability to preserve visual function in real-world clinical care. These findings beg the bigger question: if SLT can reduce the risk of rapid VF progression while freeing patients of the side effects, hassles, and costs of daily self-administration of medical therapy, why is medical therapy still the preferred first-line treatment for most ophthalmologists?