  In this work we develop and investigate mathematical and computational models
that describe drug delivery from a contact lens during wear. Our models are
designed to predict the dynamics of drug release from the contact lens and
subsequent transport into the adjacent pre-lens tear film and post-lens tear
film as well as into the ocular tissue (e.g. cornea), into the eyelid, and out
of these regions. These processes are modeled by one dimensional diffusion out
of the lens coupled to compartment-type models for drug concentrations in the
various accompanying regions. In addition to numerical solutions that are
compared with experimental data on drug release in an in vitro eye model, we
also identify a large diffusion limit model for which analytical solutions can
be written down for all quantities of interest, such as cumulative release of
the drug from the contact lens. We use our models to make assessments about
possible mechanisms and drug transport pathways through the pre-lens and
post-lens tear films and provide interpretation of experimental observations.
We discuss successes and limitations of our models as well as their potential
to guide further research to help understand the dynamics of ophthalmic drug
delivery via drug-eluting contact lenses.
