"Masked" pseudoexfoliation syndrome in unoperated eyes with circular posterior synechiae: clinical-electron microscopic correlation.

OBJECTIVE To investigate the prevalence of "masked" pseudoexfoliation (PEX) syndrome in eyes with circular posterior synechiae receiving antiglaucomatous therapy with miotics. DESIGN Cross-sectional prospective study. METHODS Twenty-eight eyes of 27 consecutive patients with circular posterior synechiae and a history of miotic drug use without previous intraocular surgery, inflammation, or trauma, and without conventional signs of PEX material in the anterior chamber were included in the study. All eyes were investigated by slitlamp biomicroscopy and gonioscopy of the anterior chamber before extracapsular cataract surgery for the presence of typical PEX-associated iris pigment epithelial changes, such as peripupillary atrophy and trabecular meshwork melanin granule deposition. The anterior chamber depth, lens thickness, and axial lengths of the eyes were measured by A-scan immersion sonography. The excised anterior lens capsules obtained during extracapsular cataract surgery were investigated for the presence of precapsular fibrillar PEX deposits by electron microscopy. MAIN OUTCOME MEASURE The prevalence of masked PEX syndrome in eyes with circular posterior synechiae receiving antiglaucomatous therapy with miotics. RESULTS Transmission electron microscopy of unselected nonserial sections revealed a precapsular layer consisting of typical PEX fibers or microfibrils, which indicated early stages of PEX syndrome in 18 (64%) of 28 eyes with circular posterior synechiae. Melanin granules were frequently found adhering to the fibrillar layer. Eyes with precapsular fibrillar deposits showed significantly greater trabecular meshwork pigmentation than eyes without such deposits. Differences in age, lens thickness, axial length of the eye, anterior chamber depth, and degree of peripupillary atrophy were, however, not statistically significant between the groups with and without electron microscopic evidence of PEX deposits. CONCLUSIONS Circular posterior synechiae were more frequently associated with manifest or early stages of PEX syndrome. However, the formation of broad posterior synechiae in miosis prevented a definite clinical diagnosis based on the classic changes of the anterior lens capsule. In eyes with spontaneous or miotic-induced circular posterior synechiae without other obvious cause, the masked variant of PEX syndrome should always be considered.