Comparison of Latanoprost Vs. Timolol

A recent publication by our laboratory has shown that patients with ocular hypertension (OHT) have reduced uveoscleral outflow and reduced trabecular outflow facility compared with healthy age-matched controls. These changes are the cause of the elevated intraocular pressure (IOP). Aqueous flow rate did not change in these patients. It is logical to assume that it would be more efficacious to treat OHT patients with drugs that reduce IOP by increasing uveoscleral outflow (which is abnormally low) than with drugs that reduce aqueous flow (which is normal in OHT). The primary purpose of this study is to show, through a controlled masked clinical study of OHT patients, that latanoprost increases the low uveoscleral drainage of aqueous humor (Fu) back to normal levels, and timolol maleate reduces the formation of aqueous humor (Fa) below normal. Both of these mechanisms will effectively reduce IOP. The secondary purpose is to assess the effects of both latanoprost and timolol maleate on the fluorophotometric outflow facility (Cflu), and episcleral venous pressure (Pev) and on all parameters over time. 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. Subjects will be monitored for adverse events throughout the course of the study and subjects may discontinue from the study at any time for any reason, or may be discontinued if, in the opinion of the investigator, there is a risk to the subject.