Effects of prolonged intracameral perfusion with mock aqueous humour on the morphology of the primate outflow apparatus.

The eyes of six pig-tailed macaques (Macaca nemestrina) were exposed to mock aqueous humour (Barany's fluid) at pressures within the physiological range for 4 hr in vivo. The eyes were perfuse-fixed at 18 mmHg in situ. The anterior segment tissues were studied by light microscopy, transmission- and scanning electron microscopy. The outflow apparatus of these perfused eyes showed marked structural changes when compared with non-perfused eyes. These changes included the narrowing of Schlemm's canal and a loss of trabecular endothelial cell cytoplasmic processes in the trabecular meshwork. The cribriform layer showed a loss of cell-to-cell contact and a washout of extracellular materials. The incidence of 'giant vacuoles' was increased in perfused eyes and the lining endothelium was also characterized by focal ballooning which occasionally occluded the collector channels. These morphological disturbances could not be attributed to pressure and were probably due to over exposure to mock aqueous humour which may have weakened cell-to-cell adhesion.