Posterior vitreous fluorophotometry in normal subjects.

We performed vitreous fluorophotometry using the Fluorotron Master and intravenous fluorescein injection of 14 mg/kg of body weight in 22 normal subjects. Various methods of analysis were used to evaluate vitreous fluorescein concentration at 3 mm from the retina as well as averaged over the posterior 6 mm. The various methods of calculation yielded mean (+/- SD) postinjection values ranging from 1.7 +/- 1.4 to 4.3 +/- 2.3 ng/mL at 30 minutes and from 7.1 +/- 2.4 to 10.8 +/- 2.7 ng/mL at 60 minutes. The permeability index determined 60 minutes after injection ranged from 0.92 +/- 0.40 X 10(-7) to 1.19 +/- 0.30 X 10(-7) cm/s, according to the protocol used. Replicate pairs of measurements in six subjects demonstrated that the procedure was reproducible to within 17% to 49%, depending on the analysis. The results suggest that if the current methods of data analysis are used, fluorescein leakage might be considered abnormally high if at 60 minutes the 3-mm posterior vitreous fluorescein concentration corrected for background fluorescence exceeds 14.3 ng/mL and/or the permeability index exceeds 2 X 10(-7) cm/s.