The Institutional Review Board of the University of Miami School ofMedicine approved this project. A prospective, randomized, controlled clinicaltrial was performed at the Bascom Palmer Eye Institute on the patients of3 vitreoretinal surgeons (M.S.B., T.G.M., and C.W.G.E.); these patients underwentpars plana vitrectomy with long-acting gas tamponade, met inclusion and exclusioncriteria, and consented to enroll in the study. The patients were 18 yearsor older and had an IOP on preoperative examination higher than 5 mm Hg andlower than 22 mm Hg. Exclusion criteria included a current or prior diagnosisof glaucoma, current use of a glaucoma medication, chronic or recurrent uveitis,a history of corticosteroid response, the presence or planned placement ofan anterior chamber intraocular lens, a history of hypersensitivity to anyof the study medications, obstructive airway disease, second- or third-degreeheart block, or current use of tricyclic antidepressants. Patients were randomizedpreoperatively with a randomly permuted block scheme in which the block sizevaried between 1 and 4, with an equal number of patients randomized to eachof the 4 treatment groups at the end of each block. After patient eligibilitywas determined, the examining physician called the Biostatistics Center, whichassigned the patient to 1 of 4 treatment groups: (1) 0.5% timolol–2%dorzolamide (Cosopt; Merck & Co, Inc, Whitehouse Station, NJ), (2) 0.5%timolol gel-forming solution (Timoptic XE; Merck & Co, Inc), (3) 2% dorzolamide(Trusopt; Merck & Co, Inc), or (4) a placebo drop (artificial tears) (acombination of dextran 70 and hydroxypropyl methylcellulose [Tears NaturaleII]; Alcon Laboratories, Inc, Fort Worth, Tex). The baseline characteristicsof the treatment groups are given in Table1.