Patients with a CRAO usually have significant comorbidities such as hypertension, atherosclerosis, or diabetes. These patients are at risk for additional morbidity and require prompt medical referral to determine the etiology of the CRAO. Medical testing should include blood pressure evaluation, electrocardiography, echocardiography, blood glucose management, lipid and cholesterol testing, and hyperviscosity studies. Any irregularities or abnormal studies will require further evaluation. Patients over the age of 60 need an immediate erythrocyte sedimentation rate (ESR) test in consideration of the possibility of giant cell arteritis.