As part of a quick point-of-care ultrasound (POCUS) examination, ocular ultrasound can help determine increased intracranial pressure (ICP), retinal detachment, lens dislocation, vitreous hemorrhage, etc. in conjunction with the patient’s history and physical exam.
For increased ICP, I’ll place a Tegaderm on the patient’s closed eye (avoiding air bubble entrapment), apply ultrasound gel, and use a high-frequency linear probe to obtain the pictured view. I locate the optic nerve sheath entering the posterior globe, measure 3 mm posteriorly, and then measure the optic nerve sheath across.
A diameter < 5 mm is generally considered “normal” whereas > 6 mm suggests increased ICP. 5-6 mm is indeterminate. Notice how these measurements are in millimeters, and the values for normal and abnormal are so close to each other. Lots of room for error, so the clinical context must be considered! Additionally, using the same POCUS view, papilledema can be determined by optic disc protrusion into the vitreous body (not seen in this image, but it would be where the yellow triangle is).
Drop me a comment below with your experience and questions regarding ocular ultrasound!
