A Newly Designed Glaucoma Drainage Implant Made of Poly(styrene-b-isobutylene-b-styrene)

Abstract

clinical evaluation, flow patency, and histopathological findings of a novel glaucoma drainage implant (GDI) made of poly(styrene-b-isobutyleneb-styrene) (SIBS) in rabbits. Methods: In 16 normal eyes, the proximal end of the SIBS GDI was inserted into the anterior chamber while the distal end was placed in the subconjunctival space. A control group underwent implantation of a similarly designed silicone GDI. Slitlamp follow-up and intraocular pressure measurements were recorded. Flow patency was evaluated by injecting 0.01% fluorescein into the anterior chamber. Immunostaining against collagen IV, macrophages, and ␣ smooth muscle actin was performed. Results: Slitlamp examination suggested adequate biocompatibility. A low and diffuse bleb was observed in the SIBS group. All SIBS tubes were patent 6 months after insertion. Immunostaining demonstrated noncontinuous collagen deposition. No macrophages or myofibroblasts were visible around the SIBS tubes. In contrast, silicone induced collagen deposition and myofibroblast differentiation. Conclusion: This new GDI is clinically biocompatible in the rabbit and maintained 100% patency at 6 months. A remarkable difference was the absence of myofibroblasts in the surrounding tissue in the SIBS group. Clinical Relevance: This novel GDI made of SIBS would prevent the feared complication of hypotony and will decrease the amount of subconjunctival fibrosis.

A new manner of reporting pressure results after glaucoma surgery

“…Out of the 65 abstracts on glaucoma surgery, 28 of them were not relevant to our inquiry: six presented animal or laboratory studies,2–7 four discussed short-term results (ie, hours/days after surgery),8–11 seven were reviews,12–18 nine presented case studies,19–27 and two contained statements insufficiently supported by the furnished data 28,29…”

In vivo biocompatibility assessment of (PTFE–PVDF–PP) terpolymer-based membrane with potential application for glaucoma treatment

“…Only in studies evaluating implants made of catgut and its polymers mild clinical symptoms were observed 1 month after surgery [22, 23]. They include proliferation of capillaries in sclera, inflammatory infiltration around implant [18, 20–22, 24, 25], proliferation of connective tissue around implant [20, 26], granular reaction [18, 20, 24], fibrosis [18, 20], inflammation around sutures [18, 23]. As it results from available literature the lesion sites increase within the period of 14–30 days after surgery, what may be associated with a natural healing process and tissue reconstruction after surgery.…”

Medical applications of poly(styrene-block-isobutylene-block-styrene) (“SIBS”)

“…It was discovered during this first set of implants in rabbits that SIBS barely encapsulates in the eye as compared to PDMS, which demonstrates significant encapsulation and concomitant angiogenesis. The first application leveraging this finding was a glaucoma drainage tube, called the ''MIDI-Tube'', first described by Acosta et al [54] from Parel's group. The MIDI-Tube, illustrated in Fig.…”