Attempts at reverse perfusion of the trabecular meshwork in different monkey species (Cercopithecus ethiops, Macaca mulatta, and Macaca speciosa).

I A small plastic bell connected to a reservoir suspended on a strain gauge and to a pressure recorder was fixed over a fistula in the scleral wall of Schlemm's canal. The anterior chamber was similarly connected to a reservoir and a pressure transducer. In a majority of vervet eyes an increase of the pressure in the bell over the intraocular pressure caused a bulk inflow into the canal through the bell and a reflux from the anterior chamber to its reservoir. Thus reverse perfusion of the trabecular meshwork from the inflated canal took place. Conventional facilities seen from the anterior chamber increased with increasing pressure in the bell. Analysis of the data indicate that the increase in facility is due to several factors. In the inflated region scleral resistance is short-circuited. Probably inflation of the canal also increases facility by reducing the area of normally collapsed regions of the canal where little filtration can take place. Moreover, a gradual change in size of the inflated region depending on the pressure relations between anterior chamber and canal appears as a facility during reverse perfusion. In the rhesus monkey the inflow from the bell became fast at high pressure levels, but no detectable reverse perfusion took place and the facility was not changed. The reason for this behavior is not quite clear. In the one stumptail eye tested, no inflow from the bell was achieved.