The development of SIBS (poly[styrene-block-isobutylene-block-styrene]) began in the cardiovascular arena, when Dr Pinchuk observed that conventional biomaterials underwent slow biodegradation and concomitant inflammation as a result of a foreign body reaction in humans. This could have negative long-term consequences for patients. As a result, Dr Pinchuk and his team of biomedical engineers set out to create a degradation-resistant biostable polymer to enable the development of novel implantable products that would otherwise fail using conventional materials.^1,2

The developmental breakthrough was found in a family of biostable polymers developed a decade earlier at the University of Akron and subsequently licensed by InnFocus, whose experts then reformulated and purified it, rendering the material medical grade.

The foundation of the remarkable biostability of SIBS is the base polymer, comprised of a central polyisobutylene block capped on both ends with polystyrene.  This triblock polymer has no sites for degradation and no risk of forming brittle double bonds that could affect its longevity in the body when flexed.^1,2

After modifying the base formula to improve reproducibility, manufacturing, handling, and functionality, and then purifying the polymer for implantable applications, Dr Pinchuk’s team achieved the goal of developing a degradation-resistant biostable polymer. SIBS was first used in cardiology to create a small, balloon-expandable, drug-eluting stent that helped prevent restenosis without the risk of biodegradation, inflammation, and vessel occlusion.1 This success with SIBS led the team to explore other surgical applications that would benefit from a degradation-resistant biomaterial.^1-3

Dr Pinchuk and a partner team of ocular experts explored the best approach to incorporating SIBS into a surgical device for glaucoma.3 Following testing of SIBS implants in an animal model, InnFocus was formed in 2004 to develop SIBS-based products for ophthalmology, with a primary focus on glaucoma.^1,2