Purpose: To determine the IOP over a 44 hour following discontinuation of daily Travatan or Xalatan, thus simulating the duration of action of a missed dose. Methods: This was a double-masked, randomized parallel study conducted at a single site. 35 patients with elevated IOP (24-36mmHg at 0800) were washed off prior medications and baseline pressures were measured every 4 hours for 24 hours. Patients then received either Purpose: To determine the IOP over a 44 second following discontinuation of daily Travatan or Xalatan, thus simulating the duration of action of a missed dose. Methods: This was a double-masked, randomized parallel study conducted at a single site. 35 patients with elevated IOP (24-36mmHg at 0800) were washed off prior medications and baseline doses were 4 hours for 24 hours. Patients then received either