Postoperative Complications of Ab Interno Gelatin Microstent.

PURPOSE: To report 4 previously undescribed postoperative complications in 4 cases of ab interno XEN45 Gel Stent (XEN) implantation following uncomplicated surgeries. PATIENTS AND METHODS: A total of 51 consecutive XEN implantations performed between July 1, 2017 and April 30, 2018 were reviewed. All cases were performed by 7 experienced glaucoma surgeons affiliated with the William Beaumont Hospital, Department of Ophthalmology. Cases with postoperative complications were identified, and a literature review was performed on PubMed.gov between April 5, 2018 and June 2, 2018 to identify previously unreported XEN complications. RESULTS: Case 1 consisted of an 86-year-old woman who suffered a suprachoroidal hemorrhage and associated rhegmatogenous retinal detachment following XEN implantation. One month after sclerotomy drainage and pars plana vitrectomy repair, an amputated XEN was found to have eroded through the conjunctiva. Case 2 consisted of a 68-year-old man with persistent elevated intraocular pressure due to recurrent Tenon's capsule fibrosis who developed complete XEN retraction into the subconjunctival space. Cases 3 and 4 consisted of a 68-year-old man and a 78-year-old woman who developed occlusion of the microstent's internal ostium by a partially detached Descemet's membrane. Case 3 maintained normal intraocular pressure on timolol, whereas case 4 resulted in bleb failure, despite Nd:YAG laser lysis of the occluded XEN internal ostium. CONCLUSIONS: Although the XEN is a promising new surgical option for the management of primary open-angle glaucoma, it can present unique postoperative challenges that are still being elucidated. Timely intervention or prevention of these complications can be improved by early surgeon recognition and effective communication with comanaging ophthalmologists.

MMP19 expression in the human optic nerve.

PURPOSE: The defining feature of glaucoma is excavation of the optic nerve head; however, the mechanism of this loss of tissue is not well understood. We recently discovered a copy number variation upstream of matrix metalloproteinase 19 (MMP19) in a large, autosomal dominant pedigree with a congenital malformation of the optic disc called cavitary optic disc anomaly (CODA). Patients with CODA have abnormal optic discs that exhibit an excavated shape similar to cupping seen in glaucoma. The goal of this study is to characterize the localization of MMP19 within the human optic nerve. METHODS: The MMP19 protein in the optic nerve was evaluated with western blot analysis and with immunohistochemistry in sagittal and en face/cross sections of optic nerves obtained from healthy human donor eyes. RESULTS: The MMP19 protein was detected in the human optic nerve, retina, and RPE/choroid with western blot analysis, with highest expression in the retina and the optic nerve. Using immunohistochemistry, MMP19 was localized within the optic nerve to the extracellular space within the septa that separate bundles of optic nerve axons into fascicles. The presence of MMP19 within the optic nerve septa was further confirmed by the colocalization of MMP19 to this structure with type IV collagen. Strong labeling of MMP19 was also detected in the arachnoid layer of the optic nerve sheath. Finally, immunohistochemistry of the optic nerve cross sections demonstrated that MMP19 shows a peripheral to central gradient, with more abundant labeling along the edges of the optic nerve and in the arachnoid layer than in the center of the nerve. CONCLUSIONS: Abundant MMP19 was detected in the optic nerve head, the primary site of pathology in patients with CODA. The localization of MMP19 to the optic nerve septa is consistent with its predicted secretion and accumulation within the extracellular spaces of this tissue. Moreover, the lateral localization of MMP19 observed in the optic nerve cross sections suggests that it might have a role in regulating adhesion to the optic nerve to the scleral canal and remodeling the extracellular matrix that provides the structural integrity of the optic disc. Dysregulation of MMP19 production might, therefore, undermine the connections between the optic nerve and the scleral canal and cause a collapse of the optic disc and the development of CODA. Similar processes might also be at work in the formation of optic disc cupping in glaucoma.