Twelve healthy, male, nonsmoking volunteers were included in the study. All subjects signed a written informed consent to participate. The study protocol was approved by the Ethics Committee of the Medical University of Vienna and adhered to the guidelines of Good Clinical Practice and the Declaration of Helsinki. Each subject passed a screening examination, including medical history, physical examination, and a 12-lead electrocardiogram. Furthermore, an ophthalmic examination, including slit lamp biomicroscopy and indirect funduscopy, was performed as part of the prestudy screening. Inclusion criteria were normal ophthalmic findings, ametropia of less than 3 D, anisometropia of less than 1 D, and an IOP between 10 and 18 mm Hg measured using applanation tonometry. Subjects were excluded if any abnormality was found unless the investigators considered it to be clinically irrelevant. An abnormality was defined as an alteration from the normal values of the Department of Medical and Chemical Diagnostics at the Medical University of Vienna.