The effect of lens depression on the components of outflow resistance

The effect of lens depression on resistance to flow through the inner wall of Schlemm's canal, circumferentially along the canal, and through the collector channels was measured in enucleated eyes. In one series of experiments the anterior chamber was perfused while canal pressure was monitored, thus allowing us to estimate inner wall resistance and a combination of canal plus collector-channel resistance. In a second series of experiments the inner canal wall was blocked with oil while the canal was perfused, allowing us to measure both circumferential flow resistance and collector-channel resistance. Lens depression decreased inner canal wall resistance in five of five eyes and decreased circumferential flow plus collector-channel resistance in one of eight eyes. These results suggest that tensing the trabecular mesh increases canal inner wall porosity and opens the canal when it is partially collapsed.