Clinicopathologic correlation of retinal to choroidal venous collaterals of the optic nerve head.

An optic nerve meningioma developed in an elderly woman and was followed for 13 years until her death. The optic nerve was initially normal. Over time it became swollen and then atrophic and developed retinal venous to choroidal venous collaterals. Five hundred serial sections were prepared through the optic nerve and for approximately 1.5 mm superiorly and inferiorly to the optic nerve to trace the course of the collaterals that were seen ophthalmoscopically and angiographically in the optic nerve head. This clinicopathologic study shows clearly that the abnormal channels are, in fact, retinal venous to choroidal venous collaterals (bypass channels). Four collaterals extended around the end of Bruch's membrane at the optic nerve head. Two more collaterals extended through the retinal pigment epithelium to become continuous with a subretinal pigment epithelial neovascular membrane, the vessels of which connected with the choroidal vessels through a defect in Bruch's membrane.