Transmission Electron Microscopic Analysis of Trabecular Meshwork in Secondary Glaucoma After Intravitreal Silicone Oil Injection

Purpose: We analyzed morphological changes in trabecular meshwork in glaucoma developing after intravitreal silicone oil injection with transmission electron microscopy (TEM).

Methods: Specimens obtained from 2 patients after surgical trabeculectomy were fixed in McDowell fixative in one patient and in buffered formaldehyde in the other, dehydrated and embedded in Epon. Ultrathin sections were made and stained with lead citrate and uranyl acetate for TEM.

Results: In specimens mainly connective tissue sheets with disorganized and narrowed intertrabecular spaces were observed. At higher magnification the collagen sheets were composed of interstitial collagen and some of them were covered by amorphous basal membrane structures resembling material. Cellular remnants were present along the intertrabecular spaces. No other cells or clearly evident silicone oil were noted.

Conclusion: Changes such as decrease in cell content, fibrosis and build-up of basement membrane-like material have been described by other authors. They are not specific and can be seen in many secondary glaucomas. No macrophages and foreign-body granulomas in response to silicone oil were present. The pathological changes in angle structures are probably caused by other mechanisms and are not induced by silicone oil itself.