Ultrasonography of metastases and melanomas of the choroid.

Choroidal metastases and melanomas are the most common intraocular neoplasms. Choroidal metastases may appear clinically similar to other amelanotic tumors, and the diagnosis may be difficult in the absence of a history of extraocular malignancy. Ultrasonography, using A- and B-mode criteria, offers an opportunity for high accuracy in the diagnosis of choroidal tumors. However, a considerable overlapping of ultrasonographic parameters, such as tumor solidity, vascularity, and choroidal excavation, has been demonstrated for choroidal melanomas and metastases. We have found that choroidal metastases are characterized by a significantly lower height-to-base ratio than melanomas, whereas reflectivity is significantly higher in metastases. Thus the combined use of height-to-base ratio and reflectivity provides a highly significant differentiation between choroidal melanomas and metastases. This observation has further improved the diagnostic value of ultrasonography in the differentiation of choroidal tumors.