Ocular ultrasonography focused on the posterior eye segment: what radiologists should know

Ocular B-mode ultrasonography (US) is an important adjuvant for the clinical assessment of a variety of ocular diseases. When ophthalmoscopy is not possible, mainly due to opacification of the transparent media (e.g., mature cataract or vitreous haemorrhage), US can guide the ophthalmologist in diagnosing disease and choosing treatment. The superficial location and cystic structure of the eye make US ideal for imaging of the eye. Moreover, dynamic study helps distinguish between various conditions that would otherwise be difficult to differentiate in some clinical setting, such as vitreous, retinal, and choroidal detachment. US is also good technique for detecting other pathologic conditions such as lens dislocation, vitreous haemorrhage, asteroid hyalosis, optic disc drusen, and tumors (e.g., choroidal melanoma, metastases, hemangioma). An understanding of the basic anatomy of the eye, the US technique, and common entities that affect the ocular globe will allow radiologists to offer this valuable imaging modality to patients and referring clinicians. This article focuses on the US anatomy and pathologic conditions that affect the posterior ocular segment.