Meta-analysis finds contralateral IOP reduction after unilateral selective laser trabeculoplasty

This systematic review and meta-analysis assesses the effect of unilateral selective laser trabeculoplasty (SLT) in primary open-angle glaucoma (POAG) and ocular hypertension (OHT) eyes on contralateral eye intraocular pressure (IOP). A literature search was performed in PubMED, EMBASE, and Cochrane Library. We included all English randomised controlled trials, retrospective and prospective cohort studies, cross-sectional studies and case series published between 29 August 2004 and 29 August 2024 that performed unilateral SLT in POAG or OHT eyes with contralateral eye IOP reported at least 3 months after SLT. Risk of bias was assessed using the ROBINS-I tool. Meta-analysis was performed using the random-effects model and presented as forest plots. 9 studies (478 eyes) were included in the final pooled analysis, which demonstrated a mean contralateral IOP reduction of 1.85 mmHg (95% CI [1.23, 2.47]) 3-6 months after SLT. Subgroup analysis found a mean contralateral IOP reduction of 2.21 mmHg (95% CI [1.06, 3.36]) and 2.29 mmHg (95% CI [1.30, 3.29]) 3-6 months following 360° (4 studies, 264 eyes) and 180° SLT (2 studies, 55 eyes) respectively; there was no significant difference between both groups (p = 0.91). Meta-correlation analysis of 3 studies (160 eyes) found moderate positive correlation between IOP reduction in SLT-treated and contralateral eyes at 3-6 months (pooled Pearson's R = 0.65, 95% CI [0.54, 0.73]). Our meta-analysis suggests statistically significant contralateral IOP reduction 3-6 months following unilateral SLT, which was correlated with IOP reduction of SLT-treated eyes. These findings may have implications on future SLT studies and real-life clinical practice.Review Registration The protocol for this review was registered with PROSPERO (ID: CRD420251013653).