B-scan ultrasonography of orbital lymphangiomas.

Unilateral exophthalmos is an important clinical ophthalmic problem. A clinical diagnosis of the cause of the exophthalmos is often very difficult. B-scan ultrasonography is an important new diagnostic modality with great potential in determination of the nature of orbital pathology. The earliest ophthalmic applications of ultrasound were reported by Mundt and Hughes (I956). A-scan ultrasound, as described by Oksala and Lehtinen (I957), Gernet (I963), and Ossoinig (I969), is now widely used. B-scan ultrasound was initially utilized in only a few laboratories (Baum and Greenwood, I958; Purnell, I965) because of the high cost and complexity of early B-scan instrumentation. B-scan equipment has recently become more readily available (Coleman, Konig, and Katz, I 969). B-scan ultrasound yields two-dimensional "acoustic sections" of the eye and orbit and is the technique of choice for orbital diagnosis. The difference between ultrasonic Aand B-scans is shown diagrammatically in Fig. I.