Morphology and function of the aqueous outflow system in monkey eyes perfused with sulfhydryl reagents

The aqueous outflow system from anterior chamber to Schlemm's canal was examined by electron microscopy in pairs of enucleated macaque and baboon eyes, perfused via the anterior chamber with mock aqueous humor in one eye and the same fluid with added iodoacetamide (IA) or N-ethyl maleimide (NEM) in the other eye. Many details of the electron micrographs were analyzed in a masked manner using a digitizing bit pad and computer, and also using visual evaluation. Both IA and NEM increased aqueous humor outflow facility, but the morphologic changes induced by IA were quantitatively different from those induced by NEM. Intercellular junctions were not affected by IA, but were disrupted by NEM (P less than 0.01). Vacuoles in the endothelial lining of Schlemm's canal tended to increase in area, but not in number, under the influence of IA, whereas they were not so affected by NEM. No loss of extracellular material was observed in either IA- or NEM-treated eyes. The results indicate that the chemical status of cellular-SH groups may influence aqueous humor outflow facility at multiple sites in the outflow pathway.