Optic Nerve Ischemia Secondary to Pediatric Orbital Cellulitis

FIG. 1FIG. 2Diffusion-weighted imaging (DWI) is a specific sequence of magnetic resonance imaging (MRI) that estimates the rate of water diffusion. The apparent diffusion coefficient (ADC) image, on its turn, is a form of quantifying the diffusion of water in DWI. Obstacles to water diffusion include cellularity and ischemia, which are seen with high signal intensity in DWI and low signal intensity in ADC. We describe the case of an 11-year-old boy who presented with left rapid-evolving cellulitis and globe tenting (Fig. 1A, massive left hemifacial and eyelid edema; Fig. 1B, axial computed tomography scan) that resulted in complete visual loss even after urgent cantholysis and drainage of a circumferential orbital abscess (Fig. 1C). On the first postoperative day, DWI (Fig. 2A) and ADC (Fig. 2B; optic nerves ADC values: right 1.034 s/mm2, left: 0.63 s/mm2) showed restricted diffusion along the entire extension of the left optic nerve (ON) indicating ischemia. The authors believe that the optic nerve ischemia resulted from the compression of the optic nerve pial vessels by the acute orbital compartment syndrome. Orbital hypertension also compressed the short posterior ciliary arteries and central retinal artery causing retinal and choroidal ischemia (Fig. 2C,D; optical coherence tomography: edema and complete disorganization of retinal layers). This case highlights that optic nerve ischemia is a mechanism of visual loss in orbital compartment syndromes.