Ocular pain and trauma, vision loss, foreign body
- Retinal Detachment: look for a thin hyperechoic membrane floating about in the posterior globe, tethered to the posterior aspect of the globe at the optic nerve. Concomitant retinal hemorrhage can be seen with hyperechoic fluid behind the retina. A retinal detachment will usually remain tethered to the optic disc and will remain more "linear" and stationary and not as "wavy" and undulating as a Vitreous Detachment. A vitreous detachment will not remained tethered at the disc.
- Vitreous Hemorrhage: look for linear swaying hyperechoic material in the posterior globe (“Seaweed Sign”). When the patient looks side to side, they will exhibit “aftermovements”- and continue to swab about after the eye movement has stopped.
- Foreign Body: look for any hyperdense material in the anterior/posterior chambers, this is useful for identifying objects often missed on CT (i.e. wooden splinters) and to assess depth prior to FB removal.
- Attempt to use color doppler and pulse wave doppler to visualize the ophthalmic and retinal vessels. This can be useful for CRAO and retrobulbar hematoma identification.
- Gain: “Undergaining" will miss pathology and “Overgaining” can lead you to overcall pathology by bringing artifacts into view (these will disappear when the gain is lowered, pathology such as a vitreous hemorrhage, will not). In general though the gain will need to be turned up to the point where the vitreous is echolucent (black), you can use the unaffected eye as a guide. A generous pillow of STERILE gel (Surgi-Lube) will help with this and also prevent pressure on the globe in the case of suspected globe trauma/rupture.
- Eye motion: the patient should be instructed to look back and forth when scanning for pathology. Looking to the extreme side can cause a posterior artifact from the anterior chamber/lens, this will disappear when looking straight on.
- Optic Nerve Measurements: use calipers to measure 3 mm posterior to the retina, at this level you should measuring the diameter of the hypoechoic optic nerve
- infants (1 year or less) ≤ 4mm
- children ≤ 4.5mm
- adults should be ≤ 5mm