Inward permeability of the blood-retinal barrier by fluorophotometry

A method for assessing the inward permeability of the blood-retinal barrier by fluorophotometry is presented. The permeability value is calculated with the fluorophotometer computer from fluorophotometric scan values in vitreous and non-protein-bound fluorescein concentration values in plasma. No diffusion coefficient of fluorescein in vitreous was required in the calculations. Corrections were performed for lens transmission, corneal transmission, and the spatial resolution of the apparatus. The method was applied to 58 healthy volunteers, aged 13-72 yr. An insignificant average increase of permeability values was found from 4.8 nm/s at 10 yr, up to 6.1 nm/s at 70 yr (P = 0.14; standard deviation: 1.8 nm/s). Permeability values showed an average increase of 10% between 30 min and 60 min after injection (P less than 0.001).