A novel suprachoroidal microinvasive glaucoma implant: in vivo biocompatibility and biointegration.

BACKGROUND: A major challenge for any glaucoma implant is their ability to provide long-term intraocular pressure lowering efficacy. The formation of a low-permeability fibrous capsule around the device often leads to obstructed drainage channels, which may impair the drainage function of devices. These foreign body-related limitations point to the need to develop biologically inert biomaterials to improve performance in reaching long-term intraocular pressure reduction. The aim of this study was to evaluate in vivo (in rabbits) the ocular biocompatibility and tissue integration of a novel suprachoroidal microinvasive glaucoma implant, MINIject™ (iSTAR Medical, Wavre, Belgium). RESULTS: In two rabbit studies, no biocompatibility issue was induced by the suprachoroidal, ab-externo implantation of the MINIject™ device. Clinical evaluation throughout the 6 post-operative months between the sham and test groups were similar, suggesting most reactions were related to the ab-externo surgical technique used for rabbits, rather than the implant material itself. Histological analysis of ocular tissues at post-operative months 1, 3 and 6 revealed that the implant was well-tolerated and induced only minimal fibroplasia and thus minimal encapsulation around the implant. The microporous structure of the device became rapidly colonized by cells, mostly by macrophages through cell migration, which do not, by their nature, impede the flow of aqueous humor through the device. Time-course analysis showed that once established, pore colonization was stable over time. No fibrosis nor dense connective tissue development were observed within any implant at any time point. The presence of pore colonization may be the process by which encapsulation around the implant is minimized, thus preserving the permeability of the surrounding tissues. No degradation nor structural changes of the implant occurred during the course of both studies. CONCLUSIONS: The novel MINIject™ microinvasive glaucoma implant was well-tolerated in ocular tissues of rabbits, with observance of biointegration, and no biocompatibility issues. Minimal fibrous encapsulation and stable cellular pore colonization provided evidence of preserved drainage properties over time, suggesting that the implant may produce a long-term ability to enhance aqueous outflow.

Wegener's granulomatosis and posterior ischemic optic neuropathy: Atypical associated conditions.

We report the atypical course of two patients with posterior ischemic optic neuropathy (PION) and Wegener's granulomatosis (WG). The first case suggests that the optic nerve could be the primary and unique localization of WG. The second case suggests retrobulbar neuritis as another manifestation of WG, secondary to the autoimmune diathesis underlying this disease.

Scanning laser polarimetry of edematous and atrophic optic nerve heads.

OBJECTIVE: To determine if scanning laser polarimetry (SLP) measures form birefringence of the retinal nerve fiber layer (RNFL). METHODS: Consecutive patients with either acute unilateral disc edema or chronic diffuse unilateral disc atrophy underwent SLP using the GDx Nerve Fiber Analyzer (Laser Diagnostic Technologies Inc, San Diego, Calif). The former group had peripapillary RNFL edema, presumably with no change in form birefringence elements, while the latter had optic nerve atrophy, presumably with a loss of birefringence elements in the RNFL. A subset of patients with acute unilateral disc edema who subsequently developed disc atrophy had repeated SLP at 6 months. Intereye and intertest comparisons of 6 SLP parameters representative of RNFL thickness were performed using the paired t test. RESULTS: In the acute unilateral disc edema group (n = 28), none of the SLP parameters were significantly increased in affected vs fellow eyes. In the chronic unilateral disc atrophy group (n = 30), all SLP parameters were significantly decreased in affected vs fellow eyes (P<.001). Patients with disc edema who had a follow-up SLP demonstrated significant declines of all parameters in the affected eyes (P<.007) but no change in SLP parameters in unaffected eyes. CONCLUSION: Scanning laser polarimetry measures form birefringence properties of the RNFL, but not necessarily the RNFL thickness.