Abstract
Abstract: :
Purpose: To determine whether differences in the optic nerve occur in eyes with primary vs secondary open angle glaucoma. Methods: Optic nerves obtained at autopsy from 36 eyes from 23 donors with primary open angle glaucoma (POAG) and 15 eyes from 10 donors with pseudoexfoliation glaucoma (PEXG) were studied quantitatively. Axon counts, fibrosis, capillary number and density were assessed in semithin sections through the postlaminar optic nerve and compared to normal age–matched autopsy eyes. Results: Marked differences in the morphology of the postlaminar optic nerve were found between POAG and PEXG. Axon loss was associated with increasing amounts of connective tissue in the septae between axon fiber bundles, and in the region surrounding the central retinal artery and vein. The fibrosis was significantly more pronounced in POAG than in PEXG. A decrease in the total number of capillaries accompanied axon loss in both POAG and PEXG. POAG nerves, however, had a decrease in the density of capillaries while in PEXG the capillary density did not change with axon loss. Arteriosclerotic changes were more common in glaucomatous eyes than in age–matched controls. Conclusions: The difference in morphology of the optic nerves between POAG and PEXG indicates that in eyes with POAG, elevated IOP cannot be the only pathogenetic factor for the glaucomatous optic nerve neuropathy. Additional factors inducing fibrosis and loss of capillaries seem to be involved. Such additional factors might also contribute to the clinical finding in POAG that nerves can become damaged without elevation of intraocular pressure.
Keywords: extracellular matrix • immunohistochemistry • neuro-ophthalmology: optic nerve