Postoperative monocular vision loss is caused by either ischemic optic neuropathy (ION) or central retinal artery occlusion (CRAO). Whereas brain MR-diffusion weighted imaging (DWI) abnormalities were reported in posterior ION (PION), a recent study showed that ON restricted diffusion may also indicate CRAO. Here we report a case of post-operative acute CRAO that highlights this neuroimaging finding.

Case Report and Literature Review

Case Report

A 71-year-old male without vascular risk factors underwent maxillary bilateral antrostomy and septoplasty for chronic sinusitis. 20-30 minutes upon awakening, he reported acute painless left eye vision loss. Visual acuity (VA) was bare light perception (left) and 20/25 (right). Facial CT was unrevealing. Fundoscopy showed retinal whitening, segmented arterioles, and hyperemic disc.  Brain MR-DWI revealed left restricted diffusion in the proximal ON with increased T2 signal. Patient received oral aspirin, intraarterial verapamil and alteplase, IV acetazolamide and dexamethasone, and topical Alphagan, and despite attempted treatments, left eye remained no-light-perception at 6-months.

We report a case of post-operative CRAO in which brain MR-DWI helped with the lesion localization. Postoperative vision loss caused by PION has normal ophthalmoscopic findings and may exhibit ON restricted diffusion.  CRAO shows retinal whitening/edema, segmentation of arterioles, and cherry-red spot on fundoscopy. A recent study reported ON diffusion restriction in non-postoperative CRAO with sensitivity and specificity of 55% and 70-100%. In our case, concurrent PION was initially diagnosed based on the MRI findings. However, given the neuro-ophthalmic findings, a proximal embolus in the CRA, obstructing its entrance into the proximal ON and exhibiting diffusion-restriction, was deemed the more likely diagnosis. In conclusion, we highlight that proximal ON diffusion-restriction on MR-DWI can be diagnostic of proximal thromboembolic CRAO. Future studies should evaluate the diagnostic accuracy and utility of MR-DWI in postoperative visual loss.