PURPOSE: To evaluate intracameral injection of mydriatics in phacoemulsification cataract surgery and compare the results with those of conventional topical mydriatics. SETTING: Department of Clinical Science/Ophthalmology, Umeå University Hospital, Umeå, Sweden. METHODS: This prospective randomized double-blind study included 60 patients who were given topical (topical group) or intracameral (intracameral group) mydriatics. The topical mydriatics comprised 3 drops of cyclopentolate 1% and phenylephrine 10% given 15 minutes apart and 150 microL intracameral lidocaine hydrochloride 1% (Xylocaine) and the intracameral mydriatics, placebo eyedrops and 150 microL intracameral cyclopentolate 0.1%, phenylephrine 1.5%, and Xylocaine 1%. The pupil size was recorded preoperatively, throughout surgery, and 1 day and 1 month postoperatively. Preoperative and postoperative corneal endothelial morphology, corneal thickness, intraocular pressure, visual acuity, aqueous cells and flare, phacoemulsification energy, duration of surgery, pulse, blood pressure, and intraoperative sensation of pain and glare were also recorded. RESULTS: With intracameral mydriatics, mydriasis reached 95% +/- 3% (SD) of its final value within 20 seconds. In the intracameral group, the pupils were smaller than in the topical group (mean 6.7 +/- 1.0 mm versus 7.7 +/- 1.0 mm, P