Composite membranes materials for ophyhalmogical implants
Ewa Stodolak, Małgorzata Krok, Teresa Gumuła, Stanisław Błażewicz
Quarterly No. 4, 2009 pages 352-357
DOI:
keywords: composite membranes, intraball implant, surgical methods for sclerectomy treatment, alginates, terpolymer
abstract Glaucoma is an disease in which increased intraocular pressure causes damages of the eye structure. This leads to destruction of ophthalmic nerve, and as a result, changes of the field of vision. As a secondary effect secondary changes in the eye structure are observed. The disease is caused by blocking of a natural porous eyeball structure so called drainage angle. Inflow of the aqueous medium from inside the eye to the anterior chamber is more difficult than in physiological state. This state leads to excessive accumulation of the aqueous medium in the eye ball. As a result, the increased intraocular pressure causes tissue ischemia and afterwards their necrobiosis leaing to atrophy of the ophthalmic nerve. The role of materials used in therapy of glaucoma is to decrease the pressure inside eye. Materials for such application should fulfill main criteria, such as biocompatibility, biostability and appropriate high porosity. Moreover, it is necessary to provide nonpenetrating filtration inside the eye. For long-term-use, the material applied for cornea implants also have to withstand static pressure and dynamic pressure changes and have to be stable in biological environment. Therefore, its durability in in vitro conditions plays an important role. A new composite material for intraocular ophthalmic implant (keratitis implant) was designed and manufactured. The composite matrix based on a synthetic non-degradable terpolymer (PTFE-PVDF-PP) with certified biocompatibility (PN-EN ISO 10993 standard). As a porogenic phase bio-degradable polymer - sodium alginate (NaAlg) in the form of powder and fibres was used. The biopolymer was mixed with terpolymer solution. Composites were manufactured by casting tech-nique followed by such a physicochemical treatment which led to obtaining appropriate porosity. This procedure enable to manufacture biomaterial possessing high open porosity with interconnected pore system. The average pore size in biomaterial remains in relation with size of porogenic phases and the type of porogenic phases (fibres or particles of NaAlg). The composite membrane is a material durable and resistant to long-term static and dynamic loads. The slight increase of total porosity and pore size which was observed after fatigue tests did not lead to deformation of the membrane material and did not lead to its destruction. Surfaces of the membrane materials were highly hydrophobic (results of wetting angle measurements and surface energy determination). That prevent adhesion of macromolecules responsible for blocking of membrane pores. High value of wetting angle were registered not only in case of distilled water but also in case of using plasma enriched with albumins. On the basis of results of these experiments new tests in in vivo conditions were continued.