gms | German Medical Science

The natural vitreous is a high-moisture, fiber-reinforced hydrogel compound material with unique biophysical properties. For the last century there has been a prolonged search for an adequate substitute, but all efforts failed to yield in an ideal and commercially available artificial vitreous. Main requirements comprise a good tamponade effect with high surface tension, sufficient buoyancy and advantageous rheological properties regarding viscosity and pseudoplasticity and cohesive attributes. The material should be inert, slowly biodegradable and transparent, should maintain a stable refractive index and shock absorbing properties. Compartmentalization of the vitreous cavity must be attained without compromising sufficient metabolic circulation. The vitreous substitute must avoid serving as a scaffold for cellular proliferation and might further inhibit proliferative activity by acting as a slow-release-system for antiproliferative drugs. Research in vitreoretinal surgery has produced numerous methodical strategies by testing a wide variety of biomaterials: Vitreous transplantation, injection of collagen or hyaluronic acid, the advent of air, gas or silicone oil instillation, the use of high-sophisticated perfluorcarbons or semifluorinated n-alcanes, and experimental approaches by using hydrogel polymers. Those tamponade materials exhibit various beneficial attributes, but they meet only some of the criteria. Therefore, the right choice of the tamponade material used is highly dependent on individual demands. A fundamental understanding of the interaction at the delicate tissue-biomaterial interface will help for future development of polymer vitreous substitutes.