Glaucomatous cupping of the optic disk by ultrasonography.

B-scan ultrasonography was used to evaluate advance glaucomatous cupping of the optic disk (0.7 cup/disk ratio or greater) in one normal subject and six patients with glaucoma. The normal eye emitted a continuous echo from the posterior pole, which conformed to its mild degree of concavity. The glaucomatous eyes emitted echos from the posterior pole, demonstrating the more extreme concavity of the optic cup. Ultrasonographic evaluation of an acrylic plate containing holes of known diameter demonstrated the limits of resolution and artifacts that resulted from this examination.