ABSTRACT: In randomized, controlled trials of open-angle glaucoma (OAG) or ocular hypertension (OHT), bimatoprost 0.01 % improved tolerability while retaining the intraocular pressure (IOP)-lowering efficacy of bimatoprost 0.03 %. Given geographic/racial differences in glaucoma presentation, the APPEAL study assessed the occurrence and severity of hyperemia produced by bimatoprost 0.01 %, and its efficacy, in the Taiwanese clinical setting.In this multicenter, open-label, observational study, treatment-naïve and previously treated patients with OHT or OAG received once-daily bimatoprost 0.01 % for 12 weeks. Hyperemia (primary endpoint) was graded at baseline, week 6, and week 12 using a photonumeric scale (0, +0.5, +1, +2, +3), grouped (??+1, none to mild; ??+2, moderate to severe), and reported as unchanged from baseline, improved, or worsened. IOP assessments followed the same schedule. Supplemental efficacy analyses were conducted based on previous therapies.The intent-to-treat population (N?=?312) included treatment-naïve (13.5 %) and previously treated (86.5 %) patients; mean age was 53.3 years. At baseline, 46.3 % of previously treated patients were receiving prostaglandin analog (PGA) monotherapy. At week 12, 91.2 %, 5.9 %, and 2.9 % of treatment-naïve patients exhibited unchanged, worsened, and improved hyperemia from baseline, respectively; 77.9 %, 12.9 %, and 9.2 % of previously treated patients showed no change, worsening, and improvement, respectively. There were no statistically significant shifts in hyperemia severity in either group, or in subgroups based on previous use of any PGA, any non-PGA, latanoprost, or travoprost monotherapies. In treatment-naïve patients, mean IOP reduction from baseline (18.0?±?3.8 mm Hg) was 3.6 mm Hg at week 12 (P?