Changes in the facility of aqueous outflow induced by lens depression and intraocular pressure in excised human eyes.

The effects of intraocular pressure on aqueous outflow facility and mechanical tension on the iridocorneal angle were evaluated in 44 excised postmortem human eyes. Mechanical tension on the iridocorneal angle was induced by depression of the crystalline lens posteriorly in a quantitative manner to simulate the effect of cyclotonia on the facility of aqueout outflow. In eyes perfused at constant intraocular pressure but with stepwise increases in lens depression, the increase in facility of outflow produced by the increased tension on the iridocorneal angle was minimal at low levels of intraocular pressure (2.5 and 5 mm Hg) and greatest at higher levels of intraocular pressure (10 to 25 mm Hg). Conversely, in pairs of eyes perfused over a graded series of increasing intraocular pressure, and subjected to maximal lens depression, facility of outflow remained constant until intraocular pressure exceeded 20 mm Hg; in the fellow eyes, perfused without lens depression, facility of outflow diminished linearly with increasing intraocular pressure.