[The origin of the choroidal excavation in b-scan-sonography--an experimental and clinical study (author's transl)].

In many uveal lesions a choroidal excavation can be demonstrated by B-scan-sonography. By clinical and experimental methods it can be shown that this phenomenon is elicited by differences of reflectivity between the highly reflective choroid and low reflecting uveal lesions. Therefore, the choroidal excavation is not specific for one tumor, but will always be demonstrable, when a low reflective lesion (melanoma, hemorrhage) is present in the choroid. High reflective lesions (metastases, hemangioma) do not exhibit such an excavation.