Effective treatment of posterior segment diseases depends on the ability to deliver appropriate doses of drugs to target tissues in the posterior chamber of the eye. Intravitreal injection of drug is commonly used to treat vitreoretinal diseases. In order to assess the effectiveness of the injected drug, it is critical to know the drug distribution within the eye following injection. This is particularly important when the vitreous has been replaced by substitutes since there is little understanding of the transport of drugs in vitreous substitutes. The main objective of this research is therefore to characterize the drug distribution following intravitreal injection in the vitreous chamber of the human eye with different vitreous substitutes. In the present study, different intravitreal substitutes like silicone oil, fluorosilicone oil and perfluorocarbon liquids are considered. Both direct injection of drugs and injection of a time released drug distribution are studied. The results show that the concentration distribution is highly dependent on the vitreous substitute and the diffusion coefficient of the drug. For drugs with high diffusion coefficients, convection plays a small role. For drugs with low diffusion coefficients and for vitreous fluids with low viscosity, convection is seen to play a more important role.

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