Review of the latest solutions in the use of contact lenses as controlled release systems for ophthalmic drugs

In recent years, there has been a great interest in the potential use of contact lenses as eye drug delivery systems. Static (individual layers of the cornea, sclera and retina) as well as dynamic barriers (blood flow) pose a serious challenge to the effective delivery of the drug substance to the eyeball. The current ophthalmic systems are not optimal for patients, especially in the form of eye drops, where almost 95% of the drug contained in them is lost through the process of absorption through the conjunctiva or tear drainage. This article describes in vitro experiments that examined the use of contact lenses in the context of drug treatment in infectious, inflammatory, allergic, and glaucomatous diseases. Various techniques used to modify the materials as well as their impact on drug release kinetics were discussed. It has also been demonstrated that these methods can be used in practice during in vivo research, both in animal models as well as in sick and healthy people. The advantages of using controlled-release drug systems in the form of contact lenses are the drug dosing regimen, bioavailability and the prolonged residence time of drugs in the eyeball.