Histologic studies of the vasculature of the anterior optic nerve.

Thirty-one normal human anterior optic nerves were studied in thin serial sections and their vessels stained by standard histologic stains and a new modification of the silver reticulin stain. The retrolaminar cribrosa was profusely supplied by centripetal and longitudinal vessels of pial origin; small branches of the central retinal artery were also seen. Longitudinal continuity of small vessels extended from the retrolaminar nerve to the retinal surface. This system freely anastomosed with three transverse systems; a significant anteriolar input from short posterior ciliary arteries in the sclera to the lamina cribrosa; smaller short posterior ciliary branches and occasional choroidal capillaries to the prelaminar portion; and branches derived from the central retinal artery in and around the disk. Vessels entering the prelaminar region at the level of the choroid were mainly derived from scleral branches of short posterior ciliary vessels entering through the border tissue of Elschnig, rather than from choroidal branches of ciliary arteries. Venous drainage for the anterior optic nerve was primarily through the central retinal vein, although alternate smaller paths to surrounding tissues were also identified.