Purpose: To identify factors associated with intraocular pressure (IOP) reduction following selective laser trabeculoplasty (SLT) in Afro-Caribbean people with primary open-angle glaucoma (POAG).
Design: This was a prospective stepped-wedge study.
Methods: Data were drawn from 72 Afro-Caribbean subjects with POAG participating in the ongoing West Indies Glaucoma Laser Study. Multivariable mixed-model analysis was utilized to develop a predictive model for percent IOP reduction 12 months following SLT. Putative factors (age, sex, site, baseline IOP, prior use of prostaglandin therapy, number of prewashout IOP-lowering medications, central corneal thickness, severity of glaucoma, duration of follow-up, and signs of acute postoperative inflammation) were evaluated in bivariate analysis. Factors significant at P≤0.2 were included in the final model. Right and left eye data were modeled separately.
Results: At month 12 following SLT, mean IOP reductions in the West Indies Glaucoma Laser Study were 6.2 to 6.5 mm Hg (29.7% to 31.0%) in right and left eyes. The only factor significant in both eyes (P=0.0005 in right eyes and P<0.0001 in left eyes) was time, with IOP reductions being greatest at month 3 and declining slightly over time through month 12. Vertical cup-disc ratio (P=0.006) and prior prostaglandin therapy (P=0.004) were significant only in right eyes, and central corneal thickness (P=0.014) was significant only in left eyes. Factors significant only unilaterally did not approach significance in fellow eyes, suggesting the possibility that these represent type 1 errors. Site (St. Lucia vs. Dominica) was not a significant factor, establishing generalizability of these treatment outcomes to a broader population of African-derived people.
Conclusions: This analysis did not identify any subject-specific factors consistently predictive of therapeutic response to SLT. Of note, no factors predicted a suboptimal response. These findings favorably position SLT for broad application as primary therapy in African-derived people with POAG.
Trial registration: ClinicalTrials.gov NCT02375009.