Histopathology of 8 corneal buttons after penetrating keratoplasty in silicone oil associated kerathopathy

Background: In the literature there is only a limited number of morhologica l reports on clinically diagnosed silicone oil associated keratopathy descr ibing different histological changes. The purpose of the present study was to evaluate the most common histopathological features of this disorder. Material and methods: We reviewed the registry of the ophthalmopathological laboratory at the University of Marburg with respect to the following hist opathological diagnoses: "bullous keratopathy", "endothelial-epithelial cor neal decompensation", "band keratopathy" and "endothelial degeneration". Th ese specimens were cross-checked with appropriate medical records. Eight sp ecimens with a clinical diagnosis of silicone oil induced keratopathy were identified. All specimens were examined by light microscopy. Results: Histologically, a long-standing bullous keratopathy was seen in 5 out of 8 specimens. A descemetocele was present in two other corneas. One c ase displayed band kerathopathy. A posterior collagenous layer (PCL) betwee n Descemet's membrane and the endothelium was identified in 7 out of 8 spec imens examined. This layer was of a fibrillar type in 2 corneal buttons and of a fibrocellular type in all remaining specimens with PCL. PCL was assoc iated with endothelial cell loss and degeneration. The endothelial cell den sity varied between 0 and 5 cells per high power field. Conclusion: Posterior collagenous layer associated with degenerating endoth elium appears to be the most frequent histopathological feature in silicone oil induced keratopathy. The variety of PCL in this condition makes a firm histopathological diagnosis of "Silicone oil induced kerathopathy" rather difficult.