In the elderly other common causes for hypoperfusion of the retina are thromboembolic events [2] and [3]. As a tool for the detection of TA, high-resolution ultrasonography of the superficial temporal artery has had a significant impact, with a high positive predictive value for the diagnosis of TA (specificity of 91%). However, a missing “halo” sign, suggestive for VE821 vessel wall inflammation seen on ultrasonography, does not sufficiently rule out presence of the disease (sensitivity 68%) and, therefore, superficial temporal

artery biopsy remains the gold standard in the diagnosis of TA [4]. The differentiation of embolic versus arteritic occlusion remains a diagnostic challenge in elderly patients with ischemic optic neuropathy, because symptoms of TA, such as headache and elevation of inflammatory parameters, often coexist with significant cerebrovascular risk profiles. Additionally, depending on the cause of occlusion, different acute management strategies need to be applied

quickly to improve long-term outcomes in these patients. It is evident that we still need additional criteria Atezolizumab with high negative predictive values to exclude the presence of vasculitis. In a previously published series of patients with criteria for TA and sudden blindness, we found a hyperechoic embolic occlusion of the CRA in the area of the optic nerve head, which could be used to exclude TA; we called this a retrobulbar “spot sign” [5]. Foroozan et al. published a series of 29 patients with acute vision loss irrespective of the criteria

for TA and observed this phenomenon in 9 patients with central retinal artery occlusion (CRAO) detected by retinal fluorescence angiography [6]. High-resolution Sinomenine color-coded ultrasonography can also be applied to the orbit since vitreous gel does not lead to any significant absorption of the incidental ultrasound beam. Orbital color-coded sonography (OCCS) allows detection of retrobulbar arteries and veins in addition to an assessment of orbital structures [7]. An analysis of Doppler flow spectra further aids the assessment and, to some degree the quantification, of retinal hypoperfusion due to CRA stenosis or occlusion. Normal flow velocity values within the CRA have been established previously [8]. This is the first prospective study in which patients suffering from acute vision loss due to either thromboembolic events or vasculitic changes in vessel walls were examined to identify the frequency of the “spot sign” in these specific disease patterns. We demonstrate that OCCS can be used to significantly discriminate embolic CRAO from arteritic causes of sudden ocular blindness in the elderly. The study protocol was approved by the local ethics committee at the University of Regensburg in accordance with the Declaration of Helsinki. Patients were first seen and screened at the Department of Ophthalmology of the University Hospital Regensburg.