Healthy subjects were recruited as part of a protocol approved by the Institutional Review Board of the University of Michigan Medical Center, and in accord with HIPAA (Health Insurance Portability and Accountability Act) regulations and the Declaration of Helsinki. After an initial telephone screening survey, subjects underwent an ocular screening examination. The following ocular examinations were performed: Snellen visual acuity, slit lamp biomicroscopy, intraocular pressure (IOP) measured by Goldmann applanation, gonioscopy, undilated funduscopic examination of the optic disc and posterior pole of the retina, pachymetry (Ultrasonic Pachymeter 800; DGH Technology, Exton, PA), and A-scan axial length measurements (Ultrasonic Biometer 820; Allergan Humphrey-Zeiss, San Leandro, CA). Inclusion criteria included age between 18 and 50 years, any race, either sex, and healthy, normal eyes. Exclusion criteria included pregnancy, chronic eye conditions, recent eye trauma or surgery, glaucoma medical therapy, corneal scarring, inability to cooperate for fluorophotometry measurements, less than 30 days stable dosage of systemic medications before participation in the study, anatomically narrow angle determined by gonioscopy, or recent use of glucocorticoids.