ALMOST exactly 10 years ago, Ascher1 observed an aqueous vein for the first time, laying the cornerstone for his well-known work on the visible elimination of aqueous humor in episcleral and conjunctival veins. Numerous authors have subsequently studied the significance of this visible fluid elimination and its abnormalities.
Ascher,1 Goldmann,2 and de Vries3 described an increase of the clear fluid stream in epibulbar vessels occurring during external compression of the eyeball. This is most obvious in the widening of the clear stratum in stratified recipient vessels. Usually only a few, 2 to 4, of the 20 to 30 outlets of Schlemm's canal carry aqueous humor as far as the surface of the eyeball; each of the outlets, however, may be considered the potential origin of an aqueous vein. In the normal eye, a few of these pathways are favored, owing to anatomical, and probably to small
KLEINERT HW. THE COMPENSATION MAXIMUMA New Glaucoma Sign in Aqueous Veins. AMA Arch Ophthalmol. 1951;46(6):618-624. doi:10.1001/archopht.1951.01700020632002