Retina and optic nerve diffusion restriction in acute central retinal artery occlusion: A case-control study

Objective To determine the frequency and accuracy of diffusion restriction (DR) of the retina and/or optic nerve (ON) detection on standard brain magnetic resonance diffusion-weighted imaging (DWI-MRI) in patients presenting with acute non-arteritic central retinal artery occlusion (CRAO).Methods This is a retrospective case-control study that includes all consecutive patients presenting to our tertiary academic center from 2013-2021 with acute non-arteritic CRAO (cases) or acute ischemic stroke syndrome (controls, age and gender-matched) that had brain MRI performed within 14 days from symptom onset. Two neurology residents (junior and senior), a vascular neurologist, and two neuroradiologists, blinded to the site of CRAO, independently reviewed the brain MRIs to assess for the presence of retina and ON DR. The consensus agreement between the two neuroradiologists was used to perform sensitivity and specificity analyses and calculate inter-rater reliability (prevalence-adjusted bias-adjusted kappa coefficient).Results A total of 128 patients with acute non-arteritic CRAO (mean (SD) age 69 (14) years; 50% female; median time from CRAO to DW-MRI 2 days (IQR 1-5)) and 128 age and gender-matched controls with acute cerebral ischemia were included. After the neuroradiologist consensus, DR was correctly identified in the retina or ON in 51/128 (39.8%) CRAO cases, retina alone 27.3%, ON alone 24.2%, and both retina and ON 11.7%, with almost perfect neuroradiologists' inter-rater reliability for retina (K = 0.91) and ON (K = 0.83). Among controls, the retina DR was identified in 1/128 (0.8%) and ON DR in 5/128 (3.9%). The sensitivity, specificity, positive predictive value, and negative predictive value were 28.1%, 99.2%, 97.3%, and 58.0% for retina DR, and 27.3%, 96.1%, 87.5%, and 56.9% for ON DR.Conclusions Though experienced neuroradiologists identified retina and ON DR with excellent inter-rater reliability, these are infrequent findings in real world CRAO practice, with excellent specificity but limited sensitivity. Prospective studies with larger cohort of patients, optimization of standardized orbit DWI-MRI protocols are needed to facilitate a more accurate and reliable identification of retina and ON DR in acute CRAO.