The possibility that net inflow into the eye may be altered by changes in the intraocular pressure has been discussed previously.1 Net inflow may be subdivided into secretion and ultrafiltration minus colloid reabsorption. Secretion, as defined by Kinsey, is unaltered by changes in intraocular pressure.2 Ultrafiltration, however, which is dependent on the difference between capillary pressure and intraocular pressure for its driving force, should be reduced by a rise in intraocular pressure. Hence, net flow into the eye should decrease with increasing intraocular pressure.
The mathematical basis for this concept was presented in 1963 by Bárány who used the term "pseudofacility" for the change in net inflow which occurred for a corresponding change in the intraocular pressure.3 Pseudofacility is an appropriate term for several reasons. First, it has the same units as total facility,* that is μl min-1 mm Hg-1. Second, it represents some unknown
BRUBAKER RF, KUPFER C. Determination of Pseudofacility in the Eye of the Rhesus Monkey. Arch Ophthalmol. 1966;75(5):693-697. doi:10.1001/archopht.1966.00970050695022