The use of polyisobutylene-based polymers in ophthalmology

A novel polyolefin called poly(styrene-block-isobutylene-block-styrene) (“SIBS”) originated from Joseph P. Kennedy's laboratory at the University of Akron (Akron, Ohio, United States) and was developed as a biomaterial for long-term implant applications by the author. SIBS has no cleavable groups on its backbone or sidechains, is comprised predominantly of alternating secondary and quaternary carbons on its backbone, which prevents embrittlement and cracking under flexion, and undergoes multiple purification steps which renders it extremely biocompatible and well-suited for long-term applications in the eye. This article explores two ophthalmic devices; 1) the PRESERFLO® MicroShunt (Santen Pharmaceutical Co. Ltd., Osaka, Japan) made from SIBS that lowers intraocular pressure to thwart progression of vision loss from glaucoma, and 2) a novel intraocular lens (IOL) made from crosslinked polyisobutylene, which is under-development by Xi'an Eyedeal Medical Technology Co., Ltd. (Xi'an, China) that does not glisten nor cloud over time, as do most conventional IOLs.