Mathematical models to describe drug concentration profiles of topi- cally administered drug in the anterior chamber aqueous humor have been proposed by several authors. The aim of this paper is to present a mathematical model to predict the drug concentration in the anterior chamber when a therapeutical contact lens with the drug is entrapped in nanoparticles is used. Diseases of the anterior segment of the eye are mostly treated by topical ocular administration in the inferior fornix of the conjunctiva. Nevertheless the procedure is extremely inefficient because when a drop (50 to 100�l per drop) is instilled in the eye, the ophthalmic drug has a short residence time in the conjunctival sac, less than 5 minutes, and only 1−5% of the applied drug penetrates the cornea reaching the intraocular tissues. The biovailability tends to be low and depends on the precorneal fluids dynamics, drug binding to tear proteins, conjunctival drug absorption, tears turn over, resistance to corneal penetration, nasolachrymal drainage, metabolic degradation and non-productive absorption. The absorption and the efficacy of the instilled drug can be increased by altering its formulation and/or by changing the local conditions. In the last years many researchers have proposed the use of therapeutic contact lenses to increase the ocular bioavailability of ophthalmic drugs. The first attempt to increase the residence time of the ophthalmic drug was the use of soaked contact lenses. The lens is hydrated once placed on to the cornea and releases the drug until an equilibrium is reached between drug concentration in the contact lens and in the conjunctival sac; the maximum