Peripapillary venous drainage from the choroid: a variable feature in human eyes

Drainage of blood from the choroid is thought to occur exclusively through the vortex veins in the absence of a venous equivalent of the posterior ciliary arteries. A chance observation in the peripapillary region of the choroid, inconsistent with this concept, suggested that the subject required review.

Ten nerve heads from 10 individuals were examined histologically using interrupted serial resin sections. They were obtained from eyes free of posterior segment pathology.

Peripapillary veins varying in number and size were present in seven preparations and none in the other three. All veins penetrated the sclera from the choroid close to the optic nerve head and entered the pia mater directly, receiving small veins from the laminar and postlaminar nerve head. No other locations of posterior venous penetrations of the sclera were found. This is the first description of these vessels in normal eyes; they are named 'choroidopial veins'.

Choroidopial veins represent a minor and inconstant route for blood drainage from the choroid, with a role in optic nerve head circulation.