ABSTRACT. Vitreous fluorophotometry was used to investigate the effect of Bendazac lysine on the blood retinal barrier in 12 insulin-dependent diabetics with mild background retinopathy. The study was a randomized, double blind, cross-over trial, drug versus Placebo. Each treatment period was of 4 months. The vitreous penetration coefficient was reduced by 21% (95% c.i. 12, 30; p = 0.001) by treatment with respect to Placebo.Key words: insulin dependent diabetes -vitreous fluorophotometry -blood-retinal barrier -Bendazac lysine -Placebo -cross-over study.Acta Ophthalmol. Scand. 1997: 75: 41 -43 itreous fluorophotometry (VFPM)