The canine eye: the vessels of aqueous drainage.

Lumenal castings of canine vessels of aqueous drainage, prepared by microvascular injection of room-temperature vulcanizing silicone or Batson's methacrylate corrosion compound No. 17, were viewed with a stereo dissecting microscope and by scanning electron microscopy. The pathways for aqueous drainage in the dog appear to extend radially from the interstices of the filtering meshwork, through the deep intrascleral venous plexus, to the midscleral venous circle of Hovius, which also serves choroidal venous drainage. Venous blood mixed with aqueous humor may egress the globe from the venous plexus of Hovius via the anterior ciliary vein or posterior vortex veins. The canine pathways of aqueous drainage are distinguished from those in the primate by the absence of Schlemm's canal and the intrascleral mergence of drainage routes for aqueous humor and uveal venous blood.