Effect of previous argon laser trabeculoplasty on the ocular hypotensive action of latanoprost

Purpose To study the effect of previous argon laser trabeculoplasty (ALT) on the hypotensive activity of latanoprost in primary open-angle glaucoma (POAG).Methods This was a prospective, observer-masked study. We measured the intraocular pressure (IOP) before and after 3 months of monotherapy with latanoprost in 43 eyes that had undergone a previous ALT, and in a control group (not treated with ALT) of 43 IOP-matched eyes with POAG.Results Latanoprost induced a 17.4±16.6% IOP decrease in the study group (ALT-treated eyes) and a 25.8±17.2% IOP reduction in the control eyes (P=0.02, unpaired Student’s t-test).Conclusions Latanoprost is less effective in ALT-treated eyes than in eyes with POAG not treated with ALT.