The development of a micro-shunt made from poly(styrene-block-isobutylene-block-styrene) to treat glaucoma.

Glaucoma is the second leading cause of blindness with ∼70 million people worldwide who are blind from this disease. The currently practiced trabeculectomy surgery, the gold standard treatment used to stop the progression of vision loss, is rather draconian, traumatic to the patient and requires much surgical skill to perform. This article summarizes the more than 10-year development path of a novel device called the InnFocus MicroShunt®, which is a minimally invasive glaucoma drainage micro-tube used to shunt aqueous humor from the anterior chamber of the eye to a flap formed under the conjunctiva and Tenon's Capsule. The safety and clinical performance of this device approaches that of trabeculectomy. The impetus to develop this device stemmed from the invention of a new biomaterial called poly(styrene-block-isobutylene-block-styrene), or "SIBS." SIBS is ultra-stable with virtually no foreign body reaction in the body, which manifests in the eye as clinically insignificant inflammation and capsule formation. The quest for an easier, safer, and more effective method of treating glaucoma led to the marriage of SIBS with this glaucoma drainage micro-tube. This article summarizes the development of SIBS and the subsequent three iterations of design and four clinical trials that drove the one-year qualified success rate of the device from 43% to 100%. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 211-221, 2017.

The use of poly(styrene-block-isobutylene-block-styrene) as a microshunt to treat glaucoma.

The InnFocus MicroShunt® is a minimally invasive glaucoma drainage microtube used to shunt aqueous humor from the anterior chamber of the eye to a flap formed under the conjunctiva and Tenon's capsule. The safety and clinical performance of this device approaches that of trabeculectomy with mitomycin C, the current 'gold standard' treatment for advanced glaucoma. The invention of a new biomaterial called poly(styrene-block-isobutylene-block-styrene) or 'SIBS' is the enabling factor which led to the success of this product. SIBS is ultrastable with virtually no foreign body reaction in the body, which manifests as clinically insignificant inflammation and capsule formation in the eye. The lack of capsule formation enables unobstructed flow through the 70 µm lumen tube and the achievement of controlled low intraocular pressure, which is important for the management of glaucoma. This article summarizes the integration of SIBS into a glaucoma drainage device and confirms its functionality with clinical success over a 2-year period.

Three-Year Follow-up of a Novel Aqueous Humor MicroShunt.

AIMS: An observational study to determine the safety and efficacy of filtering surgery employing a microlumen aqueous drainage device (InnFocus MicroShunt), used intraoperatively with Mitomycin C, implanted alone or in combination with phacoemulsification. MATERIALS AND METHODS: Single-site, prospective, nonrandomized study of 23 eyes that had failed maximum tolerated glaucoma medication, followed for 3 years. A MicroShunt was implanted ab externo through a needle tract under the limbus, draining aqueous from the anterior chamber to the scleral surface. Prespecified outcome measures include: intraocular pressure (IOP) control, with and without supplemental medication, success rate, medication use, and adverse events. RESULTS: Fourteen patients received the MicroShunt alone and 9 with cataract surgery. At 1 (n=23), 2 (n=22), and 3 (n=22) years of follow-up; the qualified success rate (IOP ≤ 14 mm Hg and IOP reduction ≥ 20%) was 100%, 91%, and 95%; mean medicated IOP was reduced from 23.8 ± 5.3 to 10.7 ± 2.8, 11.9 ± 3.7, and 10.7 ± 3.5 mm Hg, and the mean number of glaucoma medications/patient was reduced from 2.4 ± 0.9 to 0.3 ± 0.8, 0.4 ± 1.0, and 0.7 ± 1.1, respectively. The most common complications were transient hypotony (13%, 3/23) and transient choroidal effusion (8.7%, 2/23), all resolved spontaneously. There were no leaks, infections, migrations, erosions, persistent corneal edema, or serious long-term adverse events. CONCLUSION: Surgery with the InnFocus MicroShunt transscleral aqueous drainage tube with Mitomycin C achieved IOP control in the low teens in most subjects up to 3 years of follow-up with only transient adverse events occurring within the first 3 months after surgery.

A newly designed glaucoma drainage implant made of poly(styrene-b-isobutylene-b-styrene): biocompatibility and function in normal rabbit eyes.

OBJECTIVE: To report clinical evaluation, flow patency, and histopathological findings of a novel glaucoma drainage implant (GDI) made of poly(styrene-b-isobutylene-b-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 alpha 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.