Optic nerve sheath decompression-related perioptic pseudocysts: histo-biochemical features

Two patients (Female; 9 and 32 years in age) with papilledema secondary to venous sinus thrombosis underwent bilateral medial transconjunctival optic nerve sheath decompression for visual loss. Postoperative imaging revealed perioptic cystic lesions in 3 eyes associated with persistent papilledema and increased retinal nerve fiber layer thickness. For treatment, the cystic lesions were excised through a transconjunctival approach after aspiration of their fluid content. The cystic fluid, analyzed by gel electrophoresis, tested positive for beta-2 transferrin, confirming its cerebrospinal fluid origin. Histological examination demonstrated acellular fibrotic membranes lacking meningeal cells. Surgical excision resulted in resolution of papilledema and normalization of retinal thickness in all eyes. These findings support the classification of such lesions as perioptic pseudomeningoceles and further suggest that optic nerve sheath decompression exerts its effect through cerebrospinal fluid drainage.