Subjects eligible to participate will be at least 19 years of age and diagnosed with bilateral ocular hypertension or primary open angle glaucoma and have intraocular pressure between 20 and 35 mmHg in both eyes on Day 0. Subjects will be treated with either latanoprost or timolol for 6 weeks and then crossover and be treated similarly with the alternate drug for an additional 6 weeks. There will be a screening visit and a total of 6 study visits in which aqueous humor flow, uveoscleral outflow, and fluorophotometric outflow facility will be determined using an instrument called a fluorophotometer. The fluorophotometer scans the eye for fluorescein dye allowing the investigator to measure and calculate the above variables. There will be 7 scans taken during each study day and additionally IOP will be measured after the completion of each scan. An Exit exam will be performed at the time of exit to ensure the ocular health of the subject.