Modification of the Friedenwald-Kinsey Formula of Intraocular Pressure

The formula of the intraocular pressure proposed by Friedenwald and Kinsey is the following: IOP=k(Cap P+OP_Aq—OP_p1) where

The values k_in and k_out are the effectiveness with which the osmotic and hydrostatic forces are converted into intraocular pressure.¹ The pressure of the episcleral veins has to be considered in outflow only, but not in expressing the intraocular pressure itself.²

It seems that the effectiveness with which the osmotic and hydrostatic forces are converted into intraocular pressure is based upon their influence on inflow and outflow. The formula of the intraocular pressure can be regarded as derived from an equation of inflow and outflow, where k_in and k_out are coefficients of flow. The terms k_in and k_out are the volumes of water transferred within one minute by a pressure of 1 mm. Hg through the blood-aqueous barrier or through