A sheet metal worker with blurry vision ...
A sheet metal worker was detaching a heavy chain when it swung and hit him in the right temple. He now reports blurry vision in the nasal aspect of his right eye. Bedside ultrasound of the right eye shows the image below.
You take a look at the left eye and its looks the same. What is your differential diagnosis? What is your next step in management?
Scroll down for the Case Conclusion.
Case: A sheet metal worker was detaching a heavy chain when it swung and hit him in the right temple. He now reports blurry vision in the nasal aspect of his right eye. Bedside ultrasound of the right eye shows the image below. Interestingly, the left eye looks the same. What is your differential diagnosis? What is your next step in management?
Final Diagnosis: Drusen of the optic nerve head bilaterally
Case Conclusion: The patient had a CT of the orbits which ruled out foreign body. The CT instead demonstrated “incidental calcification of the optic nerve insertion bilaterally unchanged from prior.”
The patient followed up with Ophthalmology who diagnosed him with Drusen of the optic nerve head and normal visual acuity. He no longer requires ophthalmology follow up.
Learning Points:
Optic Nerve Drusen are yellow-white accumulations of extracellular material (proteins and lipids) beneath the retinal pigment epithelium. Drusen can be ‘hard’ (small, round, punctate nodules) or ‘soft’ (larger, pale yellow, without borders) [1]. It represents calcific degeneration of some of the axons of the optic nerve. The calcifications can be seen on both Ultrasound and CT [1]. On exam, they can mimic papilledema.
The prevalence of optic nerve drusen is estimated to be 0.4%-3.7%. Optic disc drusen can be familial and the incidence is ten times higher in family members of patients with drusen. Drusen is bilateral in 85% of cases [2].
Most cases of drusen are benign, although some people develop decreased visual acuity. 8.6% of people can have transient visual changes and estimates of 90% of people change have small visual field deficits (2, image 2). Vision loss is rare and occurs due to Anterior Ischemic Optic Neuropathy, vascular occlusions of drusen that result at the optic nerve head. Because the nasal aspect of the optic disc is more likely to have drusen, vision loss is usually peripheral. Treatment for symptomatic patients includes serial exams every 6-12 months with intraocular pressure testing and pressure lowering medications if indicated [1].
Case Conclusion by Alicia Oberle
Learn a little bit more about ocular ultrasound through this recent post at Life in the Fast Lane.
References:
1. Effron D, Forcier BC, Wyszynski RE. Chapter 3. Funduscopic Findings. In: Knoop KJ, Stack LB, Storrow AB, Thurman R. eds. The Atlas of Emergency Medicine, 3e. New York, NY: Mcgraw Hill; 2010.
Images from above.
2. Davis P, Jay W. Optic Nerve Head Drusen. Seminars in Opthalmology. 18 (4), 2003. 222-242.