Figure 6. Dynamic barriers prevent significant entry of 20 nm particles into ocular tissues in live animals. Following periocular administration of 400 µg dose of 20 nm particles to either live (blood and lymphatic circulation present) or dead rats (blood and lymphatic circulation absent) the particle levels in the ocular tissues were quantified. Higher levels of the particles are seen in the sclera-choroid, retina, vitreous, and the cornea of dead rats as compared to live rats. The data are expressed as mean ± SEM for n=4.