In the case of ischemic optic neuropathy (ION) or retinal artery occlusion (RAO), distinguishing arteritic from non-arteritic can limit or prevent irreversible bilateral blindness. Here, the utility of color Doppler ultrasonography (CDUS) in diagnosing giant cell arteritis (GCA) was evaluated. In this retrospective analysis, a total of 38 cases diagnosed with ION or RAO were included, that presented to our department in the years 2018 up to 2021 and underwent both CDUS and temporal artery biopsy (TAB). The evaluation is based on TAB as reference standard. CDUS resulted in a sensitivity of 65.0% and a specificity of 100% (when excluding two inconclusive assessments). Therefore, when limiting TAB to only suspected cases with negative or unclear CDUS findings, the sensitivity and the specificity would remain unchanged at 100%, while reducing the need for TAB by 42.1%. Overall, the data suggest the implementation of a stepwise diagnostic algorithm to confirm or rule out GCA, in which the CDUS plays a key role, thus omitting the requirement for TAB in many cases.