Objective: To evaluate dorzolamide hydrochloride in patients younger than 6 years who have an elevated intraocular pressure or glaucoma. Design: A 3-month, controlled, randomized, double-masked, multicenter, clinical trial. Patients were randomized to 2% dorzolamide 3 times daily or timolol maleate gel-forming solution (0.25% for patients < 2 years and 0.5% for patients≥ 2 but< 6 years) once daily plus placebo twice daily. If the intraocular pressure was not controlled through monotherapy, younger patients received concomitant dorzolamide 3 times daily and 0.25% timolol gel-forming solution once daily and older patients received a fixed combination of 2% dorzolamide and 0.5% timolol twice daily. The primary safety variable was the proportion of patients who discontinued therapy for a drugrelated adverse experience. Intraocular pressure reduction was a secondary measure. Results: One younger patient (1.8% )-of 56 randomized to dorzolamide discontinued concomitant therapy because of bradycardia. Two older patients (3.0% ) of 66 discontinued dorzolamide because of ocular adverse experiences. The most frequent ocular adverse experiences were discharge and ocular hyperemia (younger cohort) and ocular hyperemia and burning/stinging (older cohort). At week 12, the mean change in intraocular pressure for dorzolamide was statistically significant from baseline (-7.3 mmHg [20.6% ]-and-7.1 mmHg [23.3% ]) in the younger and older cohorts, respectively; P < .001 for both. Conclusion: Dorzolamide was generally well tolerated and demonstrated efficacy for up to 3 months in patients younger than 6 years. Objective: To evaluate dorzolamide hydrochloride in patients younger than 6 years who have an elevated intraocular pressure or glaucoma. Design: A 3-month, controlled, randomized, double-masked, multicenter, clinical trial. Patients were randomized to 2% dorzolamide 3 times daily or timolol maleate gel-forming solution (0.25% for patients <2 years and 0.5% for patients> 2 but <6 years) once daily plus placebo twice daily. If the intraocular pressure was not controlled through monotherapy, younger patients received concomitant dorzolamide 3 times daily and 0.25% timolol gel-forming solution once daily and older patients received a fixed combination of 2% dorzolamide and 0.5% timolol twice daily. The primary safety variable was the proportion of patients who discontinued therapy for a drug related adverse experience. Intraocular pressure reduction was a secondary measure. Results: One younger patient (1.8%) -of 56 randomized to dorzolamide discontinued concomitant therapy because of br The most frequent ocular adverse experiences were discharge and ocular hyperemia (younger cohort) and ocular hyperemia and burning / stinging (older cohort). At week 12, the mean change in intraocular pressure for dorzolamide was statistically significant from baseline (-7.3 mmHg [20.6%] -and-7.1 mmHg [23.3%]) in the younger and older cohorts, respectively; P <.001 for both. was generally well tolerated and designed efficacy for up to 3 months in patients younger than 6 years.