Clinicopathologic Examination of Translucent Refractile Intraluminal Tissue Coagulum From the Proximal Tube of a Baerveldt Glaucoma Drainage Device

Purpose: To describe an unusual case of glaucoma drainage tube blockage. Patients: A 76-year-old woman presented with left endothelial graft failure. Her previous ocular history included primary open-angle glaucoma diagnosed for 15 years and Fuch's endothelial dystrophy. Three years before presentation, the left eye required a Descemet stripping endothelial keratoplasty followed by a trabeculectomy with mitomycin C and subsequent Baerveldt tube insertion 3 years previously. Intraocular pressures were right 9 and left 19 mm Hg. The endothelial graft demonstrated supra-temporal edema, in proximity to the sulcus placed tube tip. Methods: A repeat endothelial keratoplasty was undertaken. During surgery, an attempt to flush the tube ab internally with balanced salt solution on a 27-G Rycroft cannula, resulted in extrusion of a long translucent tubular plug from within the silicone tube into the anterior chamber. This was removed with intraocular forceps and sent for histopathology. The endothelial keratoplasty was performed and an air bubble placed in the anterior chamber. Results: The histopathology was reported as fibrinohemorrhagic material associated with refractile material, detected under polarized light microscopy. At 6 months follow-up, the graft was clearing well, the tube in situ and the intraocular pressure 6 mm Hg. Conclusions: One possible cause of the refractile material within the specimen is spalled particles of silicone, presumably from the tube. This finding potentially questions the long-term stability of silicone products in the eye and may be a cause of capsular fibrosis around the glaucoma drainage device plate.