Ultrasound has long been an integral part of the ophthalmologist's examination of the eye and orbit. The use of ocular ultrasound was first published in 1956 and has since come to be used extensively with A-scan, B-scan, Doppler, and, more recently, 3D approaches. Both axial and longitudinal approaches are commonly employed in ED ultrasound of the eye and orbit. Due to the emphasis on recognition of acute life-threatening conditions in the ED, the application of ocular ultrasound most widely studied in the emergency medicine literature is in the evaluation of increased intracranial pressure by evaluation of optic nerve sheath diameter. Ultrasound easily allows identification of lens dislocation, vitreous hemorrhage, and globe rupture, among other traumatic conditions. ED ultrasound may also prove to be useful in the evaluation of optic neuritis. Ocular ultrasound is a relatively new ED imaging modality that is rapidly gaining acceptance among emergency clinicians.