Objective:To evaluate the 5-year sa fety and efficacy of adjunctive 0.005%latanoprost once daily.Methods:Pa-tients with primary open-angle or exfoliation glaucoma who completed a 3-year,open-label,uncontrolled,prospective trial could enter a 2-year extension phase.High-resolution color photographs of irides were tak en at baseline and at 14subsequent visits.Photographs were assessed for change in iris pigmentation compared with baseline.Intraocular pressures and adverse events were re corded.Main Outcome Measure:Development and progression of increased iris pigmentation over 5years.Results:Of the 519original patients,380enrolled in the extension phase with approx-imately 89%having an eye color known to be susceptible to color change.After 5years,most p atients had no in-crease in iris pigmentation,but certain colored irides ex-hibited notably greater susceptibi lity than others.For those whose irides did change,onset occur red during the first 8months in 74%and during the first 24months in 94%.No patient developed an increase in pig mentation after month36;the rate of progression decrease d over time.Adverse event profiles were similar for pati ents with and without increased pigmentation.The overall mean intraocular pressure reduction from baseline of25%was sustained with no need for change in intraocular pre ssure-lowering treat-ment in 70%of the eyes.Conclusion:L atanoprost therapy is safe and well tolerated for long-term treatment of open-angle glaucoma. Objective: To evaluate the 5-year sa fety and efficacy of adjunctive 0.005% latanoprost once daily. Methods: Pa-tients with primary open-angle or exfoliation glaucoma who completed a 3-year, open-label, uncontrolled, prospective trial could enter a 2-year extension phase. High-resolution color photographs of irides were tak en at baseline and at 14subsequent visits. Photographs were assessed for change in iris pigmentation compared with baseline. Intraocular pressures and adverse events were re-corded. Main Outcome Measure: Development and progression of increased iris pigmentation over 5years. Results: Of the 519original patients, 380enrolled in the extension phase with approx-imately 89% having an eye color known to be susceptible to color change. After 5years, most p atients had no in-crease in iris pigmentation, but certain colored irides ex-hibited notably greater susceptibi lity than others. For those whose irides did change, onset occur red during the first 8months in 74% and during the first 24month s in 94% .No patient developed an increase in pig mentation after month 36; the rate of progression decrease d over time. Adverse event profiles were similar for pati ents with and without increased pigmentation. The overall mean intraocular pressure reduction from baseline of 25% was sustained with no need for change in intraocular pre ssure-lowering treat-ment in 70% of the eyes. Conlusion: L atanoprost therapy is safe and well tolerated for long-term treatment of open-angle glaucoma.