The outflow tract in pigmentary glaucoma: a light and electron microscopic study.

Buttons obtained by trephination from both eyes of a 44-year-old myopic man with pigmentary glaucoma were studied by light and electron microscopy. Although clinically both eyes exhibited heavy pigmentation of the trabecular meshwork in the whole circumference, microscopically the trabecular meshwork of the left eye contained more pigment granules than that of the right eye, which appeared relatively acellular with collapse of the trabecular sheets. In both eyes endothelial cells covering the trabecular sheets were filled with pigment and showed various stages of degeneration. The intertrabecular spaces contained free pigment granules as well as cell debris. These observations suggest that plugging of the trabecular spaces by pigment and cell debris together with fragmentation and collapse of trabecular sheets contribute to the decrease in the facility of outflow that occurs in pigmentary glaucoma.