Arteriovenous anastomotic vessels in the anterior episcleral vessel network of 32 rhesus monkey eyes were delineated with 3% silver nitrate, India ink-gelatin mixture, and colored, room-temperature vulcanizing liquid silicone compound. These vessels have inside diameters of 10μ to 30μ and have muscular walls either throughout their entire length or for a short distance near their arterial origin. They usually follow a fairly direct course from artery to vein and are capable of shunting fluid flow at physiologic pressures.
Gaasterland DE, Jocson VL, Sears ML. Channels of Aqueous Outflow and Related Blood VesselsIII. Episcleral Arteriovenous Anastomoses in the Rhesus Monkey Eye (Macaca mulatta). Arch Ophthalmol. 1970;84(6):770-775. doi:10.1001/archopht.1970.00990040772016