ABSTRACT
PURPOSE: To determine the effect of acute and chronic primary angle closure glaucoma (PACG) on the trabecular meshwork. METHODS: Trabecular specimens of 16 consecutive patients with primary angle closure glaucoma (PACG)--6 acute PACG eyes, and 10 chronic PACG eyes without an acute attack--were studied by light and electron microscopy. RESULTS: Acute PACG: The trabecular meshwork revealed a generalised oedema and an accumulation of pigment in the widened trabecular spaces and Schlemm's canal. Attenuated trabecular endothelial cells appeared to be devoid of subcellular components. Chronic PACG: In chronic PACG eyes the trabecular architecture had lost its regular arrangement, with fewer and narrower trabecular spaces and fusion of the trabecular beams in areas. There were numerous electron-dense bodies in the trabecular tissues, both within the trabecular beams and in the extracellular spaces, which had a banded fibrillar structure. An overall loss of endothelial cells was noted; the remaining cells were crowded together and were polymorphic. Melanin pigment was present both within the stroma and in the endothelial cells. CONCLUSIONS: Pigment accumulation in the trabecular spaces and within the cells and a noninflammatory degeneration appeared to be the primary changes in the trabecular meshwork after acute angle closure glaucoma. In chronic PACG eyes, there was evidence of loss of endothelial cells and reactive repair processes. These changes were present in areas away from visible peripheral anterior synechiae. A gonioscopic evaluation of the extent of peripheral anterior synechiae alone may not reflect the extent of trabecular meshwork damage in acute and chronic PACG. Patients experiencing an acute attack of PACG require a long-term follow up, because the intraocular pressure (IOP) may rise later, due to ongoing changes compromising the outflow facility, or due to the effects of aging in the trabecular meshwork.