[Microscopic quantification of fluorescein distribution in retinas of normal and diabetic rats]

To identify more precisely the site and the nature of the abnormality of the Blood-Retinal Barrier (B.R.B.) in diabetes, quantitative fluorescence microscopy was used to measure time-dependent changes of fluorescence in ocular tissues of normal and diabetic rats, after intravenous fluorescein injection. Fluorescein distribution across the retinal layers was studied in control and streptozotocin diabetic rats at 5, 30 and 60 minutes after dye injection. Fluorescein intensities of choriocapillaris and retina were compared with plasma fluorescein levels. The results show a B.R.B. dysfunction in diabetic rats arising from abnormal leakage of fluorescein into the retina. After 60 minutes there was a greater fluorescence intensity localized to the inner retinal layers, consistent with a probable inhibition or saturation of active transport mechanisms for dye removal through the retinal vessels.