BACKGROUND: To compare the effect of bimatoprost and the fixed combination latanoprost-timolol (LTFC) on 24-hour systolic (SBP) and diastolic (DBP) blood pressure and on 24-hour ocular perfusion pressure (OPP).METHODS: 200 patients with glaucoma or ocular hypertension, controlled on the unfixed combination of latanoprost and timolol or eligible for dual therapy being not being fully controlled on monotherapy were enrolled in a randomized, double-masked, placebo-controlled, multicentre clinical trial. They were randomized to LTFC (8 a.m.) or bimatoprost (8 p.m.) and received 24-hour IOP curve at baseline, 6 and 12 weeks (supine and sitting position IOPs were recorded at 8 p.m., midnight, 5 a.m., 8a.m., noon and 4 p.m.). Holter 24-hour blood pressure curve was obtained between weeks 2 and 12. SBP, DBP, OPP were calculated and compared with ANOVA. Rates of diastolic OPP (DPP)≤50, ≤40, ≤30 mmHg in the 2 groups were calculated and compared using Fisher's test.RESULTS: Mean baseline SBP and DBP were 136.5±18.3 vs 134.2±20.1 mmHg (p=0.1) and 79.1±10.2 vs 78.2±10.1 mmHg (p=0.4) in the bimatoprost and LTFC groups respectively. Holter SBP was significantly higher for bimatoprost (135.1 mmHg vs 128.1 mmHg, p=0.04), while no statistically significant difference in DBP was found. DPP was similar in the 2 groups, and proportions of patients with at least one value of the 24-hour curve≤50, ≤40, ≤30 mmHg were 94%, 86%, 41% respectively.CONCLUSIONS: Bimatoprost and LTFC had similar DBPs and OPPs; SBP was significantly lower with LTFC. In this study, the percentage of "dippers" was considerably higher than the one described in previous studies on the role of perfusion pressure in glaucoma.TRIAL REGISTRATION: NCT02154217, May 21, 2014.