Histopathological and ultrastructural examination of optic nerve sheath decompression.

Both optic nerves were obtained at autopsy from a 28-year-old man with a 2 year history of idiopathic intracranial hypertension who had undergone bilateral optic nerve sheath decompression 14 days before death. Histopathological and ultrastructural examination of the tissue revealed fibroblasts localised to the sites of fenestration. Adipose tissue was also adherent to the optic nerve pia in areas of incised dura. No patent fistula site was observed. It was concluded that filtration of cerebrospinal fluid after optic nerve sheath decompression may occur through an enclosed bleb of fibrosis rather than through an open fistula.