The presence of a layer of abnormal material in Descemet's membrane in eight keratoplasty specimens served as a marker to determine whether Chandler's syndrome, Essential Iris Atrophy, and the Cogan-Reese syndrome are congenital or acquired conditions. In all eight cases of the ICE syndrome, a pattern of membrane deposition was observed, which typifies acquired disorders: a completely normal prenatal layer and both normal and abnormal portions of the postnatal layer. The thickness of the membrane deposited before the onset of abnormal secretion was used to estimate a time span for possible ages at which abnormal secretion began. The estimated age intervals for all diseased specimens had their lower limits in the postnatal period. Thus, these results led us to the conclusion that abnormal Descemet's membrane first appeared in postnatal life, years before clinical recognition of disease. The possibility of a viral etiology for this unilateral endotheliopathy resulting in an altered Descemet's membrane is discussed.