Regional differences in the structure of the lamina cribrosa and their relation to glaucomatous optic nerve damage.

Previously, there was no feature of optic nerve head anatomy or physiology that could explain the greater susceptibility for early damage in some nerve fibers by chronic glaucoma. Using a new technique for scanning electron microscopic examination of human optic nerve heads, regional differences were found in the fine structure of the lamina cribrosa. The superior and inferior parts of the lamina at the level of the sclera appear to contain larger pores and thinner connective tissue support for the passage of nerve-fiber bundles than the nasal and temporal parts of the lamina. Since the superior and inferior laminar zones are the sites of passage for arcuate area ganglion cell axons that are most susceptible to glaucoma damage, the differences found in laminar structure in these locations may explain the characteristic pattern of early glaucomatous field loss.