Fig. 17. Removal of pigment from the trabecular meshwork by macrophages in pigmentary glaucoma. A: Light micrograph of Schlemm's canal. A pigment-filled cell (black arrow) is partially inside the canal lumen and another is close to the lumen (white arrow) (600×). B: An enormously enlarged, pigment-filled cell is found entirely within the canal lumen (600×). C: Electron micrograph of the same cells as in (B). This presumptive macrophage is completely filled with melanin granules. (From Alvarado JA, Murphy CG: Outflow obstruction in pigmentary and primary open-angle glaucoma. Arch Ophthalmol 110:1769, 1992, with permission.)