The effect of intraocular pressure on conventional outflow resistance in the enucleated human eye

A technique for measuring resistance to outflow in enucleated eyes is described. The technique minimizes the artifactual effects of ocular stretching and anterior chamber deepening. Using this perfusion technique, it was found that the resistance to outflow in normal, enucleated human eyes increases directly and linearly with intraocular pressure. This phenomenon, termed the outflow obstruction effect, was defined as the fractional increase in baseline outflow resistance (outflow resistance at an outflow pressure of zero) per millimeter of Hg intraocular pressure rise above baseline and was designated by the letter Q. The value of Q was found to be 0.012 mm. Hg-1 plus or minus 0.0014 indicating that the outflow resistance rise above its baseline value approximately 1 per cent per millimeter of Hg rise in intraocular pressure. Estimates of Q, calculated from data published by other investigators over the past two decades, are also included.