The pathogenesis of reversible cupping of the optic disk in congenital glaucoma was examined by two approaches. Human fetal, neonatal, and adult eyes were examined by histochemistry and electron microscopy to delineate the embryologic development of the optic nerve head. While the neural, glial, and vascular elements of the nerve head attain their adult configuration by midgestation, the connective tissues of the lamina cribrosa are incompletely developed at birth. The response of the optic disk cup to elevated intraocular pressure (IOP) was observed in enucleated infant and adult eyes. While no disk changes were seen in adult eyes subjected to an IOP up to 90 mm Hg for 24 hours, enlargement of the disk cup in infant eyes was documented photographically and histologically after eight to 24 hours of IOP elevations to 50 mm Hg. Reversible cupping in congenital glaucoma can be best explained by compression or posterior movement of optic disk tissues-a result of the incomplete collagenous structural framework of the lamina cribrosa during late gestation and early neonatal life.
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