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Abstract
In normal human eyes which were excised after death and in which a radial iridotomu was performed to avoid artificial alteration of the depth of the anterior chamber, facility of outflow was determined by quantitative aqueous perfusion before and after dissection procedures. Internal trabeculotomy caused a large increase in total outflow facility, increasing as the circumferential extent of trabeculotomy was increased. After trabeculotomy, the facility of outflow of aqueous was no longer reduced by raising the intraocular pressure as in intact eyes. Sinusotomy, or externalization of Schlemm's canal, proved to be difficult to accomplish without injury to the inner wall. In those eyes in which sinusotomy was considered to be successfully accomplished, no detectable change was found in outflow facility until the canal was exteriorized for more than one to two hours of the circumference, but exteriorizing three hours of the circumference increased facility of outflow and exteriorizing six hours increased it still further. The facility of outflow through the exteriorized segment appeared to be relatively insensitive to variation of intraocular pressure. These experiments suggest that resistance to aqueous outflow may normally depend in part upon an intact and unyielding outer wall of Schlemm's canal against which an intact inner wall is pressed by the intraocular pressure.