**Figure 4. **Pharmacokinetic modeling of the disposition of 20 nm particles in the periocular space. Nanoparticle (20 nm) elimination from
the periocular tissue is biphasic. The solid line represents the model predicted data while the circles represent the observed
data. T_{1/2α} and T_{1/2β} represent half-lives for elimination from the periocular space. R^{2}: regression coefficient for the correlation between observed and predicted data.