Correlation of pseudoexfoliative material and optic nerve damage in pseudoexfoliation syndrome

Abstract

Purpose: To determine whether the severity of glaucomatous damage in eyes with pseudoexfoliative (PEX) glaucoma is related to the amount of PEX material in the trabecular meshwork.

Methods: Trabecular meshwork and optic nerves from 19 eyes (11 donors) with PEX syndrome were studied. Eyes were chosen to represent all stages of severity of disease. Sections from each quadrant around the circumference of each eye were studied with light and transmission electron microscopy. Morphometric measurements were made of Schlemm's canal (SC) and of the components of the cribriform region and were statistically correlated with axonal counts of the optic nerves. Correlations between clinical and histologic data were determined.

Results: Pseudoexfoliative material was frequently found in isolated aggregates beneath the inner-wall endothelium of SC. The cribriform region was otherwise normal in structure; disorganization of this region was found only in focal regions of a few eyes. The amount of PEX material was correlated with the maximal intraocular pressure (IOP) and the IOP on treatment and was inversely correlated with the number of axons in the optic nerve. The number of axons was inversely correlated with the maximal IOP and the IOP on treatment, but not with duration of disease.

Conclusions: The severity of glaucoma in PEX is related to the amount of PEX material present in the cribriform region. Elevation of IOP occurs before disorganization of the cribriform region and may be related to the location of the PEX material near the inner wall of SC. Comparison of clinical and histologic findings revealed that the results of visual field examinations fit more closely with the axonal counts than did the clinical assessment of the cup-to-disc ratio.