US of the Eye Made Easy: A Comprehensive How-to Review with Ophthalmoscopic Correlation

When performed by a trained examiner, ultrasonography (US) of the eye is a useful tool in diagnosing conditions of the ocular globe, especially when combined with ophthalmoscopy. Pathologic conditions of the ocular globe include several usual and unusual entities, most of which may be properly identified at US. For instance, the ocular globe may have an abnormal size or unusual morphologic characteristics. Lesions of the anterior chamber (eg, hyphema), lens (eg, cataract, luxation), and iris or ciliary bodies (eg, cysts) are usually seen at ophthalmoscopy but may also be depicted at US. Vitreous pathologic conditions may demonstrate echoes caused by various entities such as degeneration, asteroid hyalosis, hemorrhage, and infection, and lines are indicative of different types of detachment, including retinal, choroidal, and hyaloid detachment and retinoschisis. Posterior wall masses are usually tumors (eg, melanoma, metastasis, nevus, hemangioma) but may also result from subretinal hemorrhage or granulomas (from tuberculosis or histoplasmosis). Calcifications may be caused by drusen or be nonspecific. Foreign bodies may also be seen. Knowledge of ocular US techniques and protocols and familiarity with normal and pathologic imaging findings are critical in making a correct diagnosis.