Among various fluorophotometric methods performed on the anterior segment, topical administration of fluorescein was developed. This local administration allows to measure the aqueous humor flow and the permeability of the corneal endothelial. The examinations are performed on a computerized fluorophotometer: the Fluorotron Master. This fluorophotometer has been designed to accurately measure fluorescein's concentrations into the eye and especially in aqueous humor and cornea. Anterior chamber adapter magnifies the scan for detailed work in the anterior chamber and lens. The Fluorotron is supplied with a cuvette holder and a cuvette which is adapted to the optical head for measuring the concentration of fluorescein in blood plasma or in buffered aqueous samples. A good linearity was obtained between the meter readings and the concentrations of fluorescein in phosphate buffer with pH 7.4, within the range between 1 ng and 1000 ng. Based upon the mathematical analysis of Yablonski the method by fluorescein instillation is simple and safe and gives the loss coefficient, ko, of the dye from the anterior chamber, the aqueous humor flow, F, and the endothelial transfer coefficient kc.ca. Calculations were carried out on twenty one normal eyes yielding average values for F 2.97 +/- 0.93 microliter.min-1 (Mean +/- S.D.) and for kc.ca 4.02 +/- 0.40. 10(-1) min-1. These values are comparable to those of other authors.