This patient presents with sudden onset painless vision loss. This is the perfect patient on which to perform ocular ultrasound, because it can solidify the diagnosis of retinal detachment (RD), vitreous hemorrhage (VH), or posterior vitreous detachment (PVD) . When any of these diagnoses are made with ultrasound this decreases the likelihood of other items in the differential: retinal artery occlusion, retinal vein occlusion, amaurosis fugax, ischemic optic neuritis, cataract, or stroke. This can dramatically change your management, swinging your disposition from admit to safe discharge home with close followup. Diabetes is a risk factor for several of these causes of acute painless vision loss, and significant myopia is a risk factor for retinal detachment. Here is the original post:
Bedside ocular ultrasound has been shown to be 97% sensitive and 93% specific for retinal detachment.1
Ocular ultrasound should be performed with a closed eye, sterile jelly, and a Tegaderm on either the linear probe or on the patient’s closed eye.
Ensure that your depth is set deep enough to visualize the posterior aspect of the globe, and that you can see the optic nerve.
Have the patient look side to side (oculokinetic echography) to help differentiate RD from VH. RD will be tethered to the globe (“sheet in the wind”) and seen at low gain levels, while VH will swirl around without apparent attachment (“clothes in the dryer”) and require high gain to identify. Note that VH can occur simultaneously with RD.
RD can sometimes be confused with a posterior vitreous detachment (PVD). RD is typically seen as a thicker singular structured tethered to the optic disc that can be seen at low gain settings, while PVD is usually a thinner multilayered structure that may or may not involve the optic disc and requires a higher gain to identify.2 This results in a “swaying seaweed” appearance.1 Here is an example of PVD with some VH:
Since it can sometime be difficult to differentiate RD from PVD, it is generally recommended that the pt get very close followup with an ophthalmologist.
If a RD involves the macula, the horse is out of the barn and the patient needs urgent followup. But, if the macula is not involved, it can be spared with a corrective procedure and the pt should be seen within 24 hours. The macula is located directly in the visual axis, lateral to the optic nerve: If you draw a perpendicular line through the middle of the lens to the retina it will point to the macula.3
Yoonessi R, Hussain A, Jang TB. Bedside ocular ultrasound for the detection of retinal detachment in the emergency department. Acad Emerg Med. 2010;17(9):913-7. [pubmed]
Sharma et al. Vitreoretinal Disorders. Ultrasound Clinics 1 April 2008 (volume 3 issue 2 Pages 217-228). [article]
Dawson, Mallin. Introduction to Bedside Ultrasound, Volume 2. 2013. Apple iBook. [iBook]