The fine structure of pigment epithelium of the iris in capsular glaucoma.

An electron microscopic study was performed on the pigment epithelium of the iris in 13 patients with capsular glaucoma. Pseudoexfoliative material (PE) was often observed in small depressions or indentations of the cell membrane of the posterior pigment epithelium. PE was also found in the region where the cell membrane was indistinct and took a course perpendicular to the surface of the cell membrane. Serial sections revealed no PE in the cytoplasm of the posterior pigment epithelium. Furthermore, the PE found extracellularly was continuous with the cell membrane. Three stages were distinguished in the pigment epithelium as capsular glaucoma progressed. At an early stage (stage 1), the number of infoldings in the posterior pigment epithelium increased, and PE was found at that site. In a more advanced stage (stage 2), the cytoplasmic processes increased in number and the basement membrane became discontinuous. In a further advanced stage (stage 3), a large amount of PE was found in the posterior chamber. The intercellular space between two adjacent pigment epithelial cells increased and the cytoplasmic processes gradually disintegrated. Only one significant correlation was found between the glaucoma stage and the stage of changes in the pigment epithelium. No associations were found between the stage of changes in the pigment epithelium and patient age or gonioscopic findings.