Our research program on biomaterials for the eye includes developmental work on templates for growing a variety of cells of the eye, and on artificial substitutes for certain segments of the eye. A substantial amount of experiments are dedicated to investigating the compatibility of the eye tissues with our materials. We also are currently developing ocular surgical adhesives and carriers for the controlled delivery of drugs and other agents to the eye.
The project is based upon a relatively new concept regarding the pump function of the corneal endothelium: the transport of fluids and ions occurs through the tight junctions between the endothelial cells, and the flow is based on the phenomenon of electroosmosis. We use synthetic polymer membranes to reproduce this process. The membranes are perforated by accelerated heavy ion beams, an operation that is done at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany. The size of channels/pores is less than 1 micrometre. We demonstrated the existence of an electroosmotic flow through a membrane perforated with channels of 100 nanometres in diameter. Work is in progress to diversify the range of polymers and further demonstrate the efficacy of the membranes. A functional prosthetic corneal endothelium should reduce considerably the need for donor tissue for corneal transplantation.
Gels injected into the eye as surgical adjuvants (viscoelastics) or as vitreous humour substitutes must stand the process of injection without breaking down into fragments. To create such a gel, our approach is to produce gels which can self-regenerate their integrity after having been fragmented and recover their initial properties. We achieved this by inserting new structural units into the polymer through the use of complex monomers that we synthesize in our laboratory. We reported the first generation of such gels in a prestigious journal and currently we are developing new monomers. A successful outcome of our project can provide an improvement in the treatment of retinal detachment, a condition affecting a large segment of population.
Preliminary research carried out at QEI by Professor Hirst indicated that none of the ocular surgical adhesives currently available on the market are satisfactory in terms of clinical results. In this project we aim at producing truly functional adhesives using two approaches: (a) improving the existing adhesives, and (b) creating new materials with adhesive properties. We will draw upon our experience with silk proteins. There is an acute need of effective adhesives in eye surgery, therefore developing a successful ophthalmic adhesive will be an important achievement.
Matrices produced from silk proteins and synthetic polymers will be evaluated for the release of incorporated bioactive agents (drugs, neuromuscular-blocking agents) in a controlled manner at the site of implantation in various segments of the eye. These devices will lead to the avoidance of frequent injections and the associated unwanted spreading of the agent, and will assure a focused and more uniform distribution of the agent into the target tissue.