Biomaterials in ophthalmic drug delivery

Polymer-based biomaterials are becoming increasingly important in ophthalmology as the number of polymers available for medical devices increases. Ocular drug delivery systems based on polymers offer the considerable advantages of improving drug availability and decreasing side effects compared to conventional therapeutic methods. Two other important ocular applications for polymers are contact lenses and intraocular lenses. In the first part, the review gives a short overview of the use of polymers in ophthalmology. The second part is focused on the synthetic, semi-synthetic and natural biopolymers used for these applications. The natural and semi-synthetic polymers discussed include cellulose-derivatives, hyaluronic acid, chondroitin sulfate, chitosan, collagen and gelatin, among others. Poly(vinyl alcohol), different polyesters, poly(alkylcyano acrylate), polyanhydrides, poly(ortho esters) and alkyl half-esters of poly(vinyl ether/maleic anhydride) represent the most widely investigated biodegradable synthetic polymers for ocular applications. The most important non-biodegradable synthetic polymers include different types of poly(acrylic acid), polyacrylamide, polyethylene, polypropylene and silicone.