PSEUDOEXFOLIATION SYNDROME WITH PEARLY DILATING PUPIL - A LIGHT AND ELECTRON-MICROSCOPIC STUDY OF THE SPHINCTER AREA

Background: The study was carried out to examine histological changes in the iris sphincter muscle and surrounding tissue in eyes with pseud oexfoliation syndrome (PXS). Methods: Seventeen patients with PXS, 14 of them having capsular glaucoma, were enrolled into the study. Iris b iopsies were obtained during extracapsular cataract extractions (ECCE) requiring sphincterotomies. Thirteen biopsy specimens underwent histo logical examination by light microscopy, and four were examined with t he electron microscope. Three iris biopsies from cadaver eyes and one obtained during ECCE from a patient with a miotic pupil (no PXS) serve d as control specimens on light microscopy. Electron microscopic contr ols included three iris specimens from cadavers. Results: In the light microscopic examination, blood vessel walls were stained with Congo R ed in seven of the 13 PXS specimens. In three of these seven specimens the stromal tissue was extensively fibrotized, and in two specimens f ibrosis was moderate. Distinct stromal fibrosis was also observed in o ne and moderate fibrosis in two PXS specimens negative for amyloid. Th e control specimens were not positive for Congo Red, but stromal tissu e was moderately fibrotized in one specimen. Light microscopy did not reveal differences in muscle tissue between PXS and control specimens. Electron microscopically, however, the muscle tissue was fibrotic or disorganized in three PXS specimens and in one control specimen. Fibri ls, similar to the fibrillar component of pseudoexfoliation material d escribed in previous studies, were found in intimate association with the capillary basal lamina in all of the PXS specimens showing muscula r fibrosis. Conclusions: These findings support the theory that PXS is associated with amyloid, and in some PXS eyes miosis is connected wit h degenerative changes both in the stromal tissue and in the muscular layer of the iris.